Toronto police say they are responding to “numerous bomb threats” made to post-secondary campuses throughout the city.

Ten campuses amongst four different schools were at the centre of the investigation, which began at 9 a.m. on Tuesday.

OCAD University said all of their buildings had been evacuated just before 10 a.m. and will remain closed for the rest of the day and evening.

“Toronto police are onsite working with OCAD University’s safety and security team,” a statement read. “We thank the OCAD University community for their prompt cooperation with today’s evacuations."

After police searched and cleared the school's campus, OCAD University said all buildings will reopen Wednesday morning "as per regular summer schedule."

Ryerson University said The Chang School had been shut down, but it has since reopened after police had “given the all clear” one hour later.

Threats were also made against George Brown College and Humber College, according to investigators.

Officers said they are working with the institutions to implement evacuations “where necessary.”

“We take these calls seriously and if they are prank calls we also look to apprehend – in the past we have apprehended people for making those accusations,” Toronto Police Chief Mark Saunders said while speaking with reporters on Tuesday.

“In the meantime, we treat it as a serious offence so I’m sure that the resources we have, who are highly trained in looking into these types of incidents, are obviously going to be going to the scene and following all of the steps in the investigation.”

No injuries have been reported.

A student at OCAD University who was forced to leave the campus said the situation was unsettling.

“We were just in class and there were police looking through the trash and then in the end they evacuated us,” she said.

“I didn’t know what to feel. I guess I was a bit scared because you don’t really hear about this that much in Canada, more in the States.”

Police are urging anyone who received a threat or has any further information pertaining to the investigation to contact them or Crime Stoppers.