Police were called to a shopping plaza Thursday morning about a roofing company's tanker truck leaking in the parking lot, the Toronto Star reported.

The plaza was evacuated and provincial environmental officials were summoned. There were concerns the tar in the storm sewers would flow into a nearby creek, so workers hustled to dump sand between the moving tar and the outlet pipes, the newspaper said.

By afternoon, the tar had hardened, and Gary Jarrett, assistant division fire chief with Brampton Fire and Emergency Services, said the area around the plaza would be prone to flooding if there was any significant precipitation.

Ontario's Ministry of the Environment issued an order to the roofing company and its subcontractor for the cleanup. The order also said the companies must also "dispose of the waste according to government regulations, document the disposal, report what caused the spill and explain how they plan to prevent future incidents," the report said.