Glass beakers and barrels of hazardous chemicals were among the items removed from a home in a quiet, residential neighbourhood in Markham where Toronto police executed a search warrant on Saturday.
Const. Allyson-Douglas Cook said officers were at the scene of the home in the Kennedy Road and Denison Street area, acting on a search warrant, along with a hazmat team.
Neighbours said the home was occupied by three men and that construction equipment could often be seen on the driveway.
"I would see them out and about sometimes but I didn't really think anything suspicious was happening in the house," said neighbour Gordon Yu.
Little more is known about the investigation — police remained tight-lipped about it Saturday — but officers at the scene told CBC Toronto police had been keeping an eye on the home for at least a few days.
Police haven't said if any arrests have been made.