Twelve Montreal youths face mischief charges after police cars were pelted with rocks Tuesday night in an east-end borough.

A group of young people gathered in a park near 15th Avenue and Maurice-Duplessis Boulevard and started lobbing rocks at nearby cars around 9 p.m. Tuesday, police said. The park is located in Rivière-des-Prairies, a borough in Montreal’s northeast.

Authorities said it’s too early to say whether there's a link between the rock-throwing incident and a riot in Montreal North on the weekend — although both boroughs are near one another.

Police also found bottles in the area that appeared to be filled with a flammable liquid, likely gasoline, although investigators will have to run tests to confirm the contents, Const. Yannick Ouimet said.

Authorities have no evidence to link the bottles to the rock-throwing, but "it's obvious someone planted them there, it's just a question of figuring out who," he said.  

At some point, a shot was fired at a city bus, but police reported no weapons were found.

Some of the 12 people arrested are minors and will appear in youth court, Ouimet said. All suspects face charges of disturbing the peace and mischief.