The RCMP will hold a news conference Saturday to talk about the arrests of as many as a dozen people on terrorism-related charges.
An officer is seen outside the police station in Pickering, Ont., Friday night. (CBC)
The charges are related to an explosives plot in Ontario, an unidentified police source said.
The suspects, described as being in their teens and 20s, were expected to be arraigned in Pickering, just east of Toronto.
On Friday, armed officers could be seen surrounding the Durham Regional Police Station in Pickering as the suspects were transported in unmarked cars, which were driven into an underground garage.
At least three police officers were armed with machine-guns as they patrolled the building, which was sealed off with yellow tape.
The RCMP say the arrests were carried out in co-operation with the Integrated National Security Enforcement Team, which is comprised of CSIS - the country's spy agency - the Mounties Canada Border Services, and Citizenship and Immigration.
The Toronto Star newspaper says some members of the group allegedly attended a "training camp" north of Toronto where they made a video imitating military warfare.