Burlington police say they are investigating a “possible bias incident” at the Vermont Workers’ Center building after a brick shattered a window that displayed a Black Lives Matter sign.

Around 9:30 a.m. Thursday, police were notified of the incident at the 294 North Winooski Avenue building, Burlington Police Chief Brandon del Pozo said. No one was injured.

Police said there were no known threats made against the Workers’ Center or its employees. Surveillance camera footage of the nearby area did not yield an image of a suspect, del Pozo said.

The Vermont Workers’ Center, along with Migrant Justice and the United Electrical Workers, organizations also based in the building, hosted a rally Thursday evening. Organizers said they believe the incident was motivated by racial bias.

“As a person of color, union member, and a worker I am extremely disheartened to see a racially motivated act of violence against our communities,” said UE member Senowa Mize-Fox, in a statement .

Police asked anyone with information to call Detective Gilligan at (802) 540-2247.