Hundreds of young people who had gathered Thursday night after a cultural event at Roseville Area High School dispersed under police orders but then started fighting at two nearby fast-food restaurants before officers broke it up, authorities said.

Three people were cut but not seriously injured by what Roseville Deputy Police Chief Joe Adams called a "sharp object," and a Chick-fil-A restaurant was reported to be extensively damaged. Officers from six law enforcement agencies were needed to restore order. No arrests were made, but the investigation was continuing, Adams said.

The fighting came a few hours after a fight broke out Thursday afternoon at Fridley High School, where a school resource officer was kicked in the head and taken to the hospital. Three teenagers were arrested after the incident, which occurred in the school parking lot at 6000 W. Moore Lake Pkwy., police said.

In Roseville, police said the fighting began outside the high school, 1240 W. County Road B2. But district spokeswoman Carrie Ardito said there was no fighting outside the school, where the Black Student Union had sponsored its annual performance show. Principal Jen Wilson said the event drew a large crowd of youth who didn't go to Roseville High but refused to leave school grounds when it was over.

Shortly before 8 p.m., young people not associated with the event arrived and were the "true agitators," Adams said. Some of the newcomers were wearing masks, so the school resource officer called for additional officers. Adams said fights erupted outside the school and continued until officers broke them up.

The crowd then moved to the Chick-fil-A at Har Mar Mall and resumed fighting, with the crowd swelling to 200. Adams said one person was cut and went into the restaurant, prompting others to barge in and break windows. It took officers a half-hour to restore order, he said.

Meanwhile, about 50 people moved the fighting to Raising Cane's near Rosedale, where there was an unsubstantiated report of gunfire. Officers eventually cleared the scene there.

Fridley Superintendent Brenda Lewis told parents in an email that the fighting that occurred there involved students who did not attend Fridley schools.