An evening of peaceful protests devolved into another night of chaos as gunfire, tear gas and Molotov cocktails flew through Ferguson, Missouri.

At least 31 people were arrested, some of whom came from as far away as New York and California, said Missouri State Highway Patrol Capt. Ron Johnson said.

For almost two hours, police in riot gear formed a barricade and stood watch as hundreds of peaceful protesters marched in a single-file line that stretched so long that different parts chanted different slogans.

"Hands up, don't shoot," some repeated. "No justice, no peace," others said. Still others were singing church hymns.

But the scene quickly deteriorated after a handful of protesters threw rocks, bottles and Molotov cocktails at police. Officers responded by firing stun grenades and tear gas canisters.

Amid the frenzy, the sounds of gunfire rang out from different parts of the city. Two people were shot within the protest site, Missouri State Highway Patrol Capt. Ron Johnson said.

One group of protesters made a barricade with portable toilets and orange cones. Some ripped out street signs, including the symbolic "Do Not Enter" sign.

Armored vehicles rolled down the streets with officers perched atop, their hands steadied on guns. Other officers darted into the protest crowd to make an occasional arrest before retreating.

Johnson, who was asked by Missouri's governor to try to keep order in Ferguson, said police are still trying to use a peaceful approach.

"For the most part it works," he said. "But tonight we had gunfire occur. Officers were taking shots at their vehicles."

He urged demonstrators to protest during the daylight hours Tuesday and not after dark.

"Make your voices heard where you can be seen and you're not the cover for violent agitators," he said.

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