PORTLAND, Ore. (AP) — Portland police made arrests after a New Year’s Eve crowd became violent, throwing fireworks, bricks and frozen water bottles at officers.

The crowd of 80 to 100 people gathered near Main Street and some engaged in violence, prompting officials to declare a riot and issue warnings to leave the area, police said in a press release.

“Few if any heeded the warning,” police said. “During the riot, participants started multiple fires. In one, a garbage can was lit ablaze and melted to the pavement. A crosswalk signal was torched, as was various debris piled in the road at Southwest 3rd Avenue and Southwest Main Street. Dangerous objects continued to be thrown at police officers.”

Police said some officers were targeted by balloons that may have been laced with a substance that caused burning to the skin. Some law enforcement officers were injured by no Portland officers were hurt.

Several businesses were damaged.

The crowd mostly dispersed by 2 a.m. Friday, police said. They were still compiling information about arrests on Friday morning and planned to release more information at a later time.