Officials said the investigation would take days, if not weeks.
The group of investigators is accompanied by monitors from the Organization for Security and Co-operation in Europe, also known as OSCE.
Foreign experts at the site are seeking human remains from the crash; the Australian foreign minister said Thursday that there could be as many as 80 unrecovered bodies.
Efforts to reach the crash site had been previously stymied by heavy fighting between pro-Russian separatists and the Ukrainian military.
Morgan reported that investigators were able to access the site after both the separatists and the Ukrainian military agreed to provide a safe corridor for entry.
Fighting surrounding the crash site, however, has remained intense, and the region is “very volatile,” according to Morgan.
Ukraine's military announced a one-day cease-fire on Thursday to allow international experts full access to the site where Malaysia Airlines Flight 17 crashed two weeks ago, officials said.
Fighting between the military and pro-Russia rebels in the area of the crash site has repeatedly prevented international monitors and investigators reaching the debris field where human remains and victims' belongings still lie scattered.
World leaders, including U.N. Secretary General Ban Ki-moon have appealed to all parties in the conflict in eastern Ukraine to halt the fighting so that the international teams can do their job.
The statement issued Thursday by Ukraine's Counter-Terrorist Operation's press center said the military would not take offensive action but will "respond to direct attacks."
The statement also accused the rebels of continued violence, including firing Grad rocket systems.
"The Russian militants do not adhere to the international agreements and demands. At 9 a.m. they used two Grad systems to shot in the village of Peremozhne. This demonstrates their attitude towards Ukraine and the international community."
The United States and others say Russia has provided arms to rebels in eastern Ukraine, including heavy weapons such as a missile system like the one believed used to down the Malaysian airliner two weeks ago.
Russia and the rebel fighters deny involvement in the shootdown of MH17.
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Mangled limbs wrapped in blood-stained rags were strewn across rooms in the school.
Run by the United Nations, the building was meant to be a refuge for more than 3,000 civilians fleeing the deadly conflict raging between Israel and Hamas in Gaza.
But shells hit it in the early morning hours as those inside slept, punching huge holes in the roof and killing at least 20 people, according to the Palestinian Health Ministry.
"We saw the shells when they hit and shrapnel was falling like rain," said Sanaa abu Gerard, a woman who witnessed the blasts. "I was so scared and the school filled with smoke. We poured water in our eyes just to see."
The deadly strike Wednesday underscores growing concerns that in Gaza, where fighting is taking place in densely populated areas, safe havens appear to be anything but safe.
It's the sixth time a facility run by the United Nations Relief and Works Agency (UNRWA) has been struck in the current conflict, intensifying questions about the tactics being used by both sides in areas crowded with civilians.
"People who go to these places expect that they go there because they will be safe," said Pierre Krahenbuhl, the commissioner-general for UNRWA. "And here is the confirmation that it appears that there is nowhere where you can be safe."
The United Nations said it thinks the rounds that hit the school, in the Jabalya refugee camp in northern Gaza, were fired by Israeli artillery. The Israeli military said it is reviewing what happened, acknowledging that it exchanged fire with militants in the area.
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While the vast majority of casualties are Palestinians in Gaza, Israel continues to ward off rocket attacks from Gaza with its Iron Dome missile defense system. Israeli officials say they are committed to destroying tunnels used by Palestinian militants in Gaza to make their way into Israel.
A poll released this week showed 86.5% of Jewish Israelis surveyed say Israel cannot accept a cease-fire because "Hamas continues firing missiles on Israel, not all the tunnels have been found, and Hamas has not surrendered," according to the Jerusalem Post.
But Israel's incursion into Gaza has had ripple effects around the world. Chile, Peru, Brazil and Ecuador have pulled their ambassadors out of Tel Aviv to protest the Israeli offensive.
It's unclear how many in Gaza want militants to stop rocket attacks.
Last month, a poll by the Washington Institute for Near East policy found most Palestinians in Gaza oppose a two-state solution and want to work toward a five-year goal of abolishing Israel. But the majority said they support nonviolent methods of "popular resistance."
Most Israelis support a two-state solution, according to a poll by the Dialog Institute, Haaretz reported.
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Facebook isn't the only social network that experiments on its users.
Online dating site OkCupid revealed on Monday the results of a study it conducted, in which it told subscribers they were more compatible than they really were. The result? There's something to the power of suggestion.
OkCupid, which is owned by Internet conglomerateIAC (), gives its users a compatibility score based on how they answer a series of questions on the site.
Among users who were just 30% compatible, a single message from one OKCupid subscriber to another led to a conversation only 10% of the time. But here's the twist: when OkCupid duped users who actually had low compatibility, telling them that their compatibility score was 90%, they had a 17% chance of having an online conversation.
"The mere myth of compatibility works just as well as the truth," said Christian Rudder, co-founder of the online dating site, in a blog post about the results of the OkCupid study,
The experiment worked in the other direction as well. That is, when users with 90% compatibility were told that their compatibility figure was only 30%, the likelihood of a conversation dropped from 20% to 16%.
OkCupid's results come after Facebook ( Tech30) caused a stir in June by revealing that it had changed the content mix in the News Feeds of almost 700,000 users in early 2012. Some people were shown a higher number of positive posts, while others were shown more negative posts.,
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A sunny day at California's famed Venice Beach took a dark turn Sunday when one person died and a dozen others were injured after a rare lightning strike.
John Kades with the Los Angeles Coroner's office told CNN a man in his mid-20's died at Marina Del Rey Hospital after being transported from Venice Beach. It's too early however to determine if he died as a result of "a lightning strike, drowning, or being trampled by the crowd," according to Kades.
Los Angeles Fire Department spokeswoman Katherine Main told CNN the lightning hit in the water and on the beach at 2:51 p.m. (5:51 p.m. ET). At least 13 patients - all of whom were either in or near the water, according to Main - were assessed on the scene, and of those, seven adults and one teenager were transported to local hospitals.
One patient had to be pulled from the water, but it was not immediately clear if it was the man who later died.
Another patient transported to the hospital was listed in serious condition Sunday afternoon, while the remaining six were listed as fair.
The National Weather Service in Los Angeles tweeted at around the time of the strike that "cloud to ground lightning" had been reported in nearby Marina Del Rey and at the Los Angeles International Airport. "Stay indoors if you hear thunder until it passes," the Weather Service tweeted.
Witnesses tweeted they saw a huge bolt of lightning strike the area, with one Twitter user describing an explosion that blew off nearby roof tiles.
Venice Beach, located south of Santa Monica in Los Angeles, is world famous for the carnival-like atmosphere along its boardwalk.
A week after Malaysia Airlines Flight 17 was shot down over war-torn eastern Ukraine, dozens more coffins containing remains of victims of the crash were due to arrive in the Netherlands on Thursday.
They will follow the first 40 wooden caskets, which were flown in Wednesday and greeted by somber, moving tributes across the country.
A lone bugler sounding the traditional military farewell "Last Post" marked their arrival at a military base in Eindhoven.
The grieving nation then held a moment of silence to honor those killed in the crash of the jetliner - caught in a war in which they had no part.
The plane was downed last week by a suspected surface-to-air missile over eastern Ukraine, where groups of pro-Russian rebels are battling Ukrainian government forces.
In a reminder of the ongoing bitter conflict, rebels claimed responsibility for shooting down two Ukrainian military jets on Wednesday. The rebels have denied that they brought down Flight 17.
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After spending days exposed to the elements on a Ukrainian field and then inside refrigerated train cars, the first group of victims from Malaysia Airlines Flight 17 are one step closer to home.
The first plane carrying the remains of some victims are expected to arrive in the Dutch city of Eindhoven on Wednesday.
The arrival will mark a homecoming for many of the victims. Most of the 298 people on board the plane were from the Netherlands, which has declared Wednesday a national day of mourning.
Dutch royals, government officials and families of the passengers will be at the tarmac when the remains arrive. After a solemn ceremony, the bodies will be taken to a military facility for forensic testing.
But Dutch Prime Minister Mark Rutte said it could take weeks or even months to identify the remains.
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A train carrying 282 bodies from Malaysia Airlines Flight 17 arrived in Kharkiv, Ukraine, getting the bodies one step closer to their grieving families around the world.
The train arrived at a rail station and continued on to an undisclosed location. The bodies will eventually be taken to the Netherlands.
But a litany of obstacles remain - not just in handling the remains, but in figuring out how and why MH17 was shot down over eastern Ukraine.
See more on this developing story on CNN.com.