Toronto police are investigating after a series of bomb threats were made against post-secondary schools around the city.

Police confirmed to CP24 that the threats, which first began at 8:45 a.m., were made against OCAD University, Ryerson University, George Brown College, and Humber College.

In total, 10 campuses were searched by police.

Investigators would not say how the threats came in but noted that the comments were all "similar in nature."

The threats prompted OCAD University to shut down all buildings on its campus on Tuesday.

"We thank the OCAD University community for their prompt cooperation with today’s evacuations," the school said in a statement released Tuesday.

OCAD later confirmed that police searched and cleared the campus and all buildings will reopen on Wednesday morning.

Ryerson University also said the Chang School was briefly closed for a police investigation but has since reopened.

“Anyone who has received a threat or has info on the investigation is asked to call police,” TPS said in a tweet on Tuesday morning.

Police Chief Mark Saunders said while the incident could be a prank, officers must treat bomb threats “very seriously.”

“In the past we have apprehended people for making those false accusations,” he said.