Hundreds of people were forced to leave two theatres on the opening night of the Stratford Festival in Stratford, Ont., after police responded to a threat.

Stratford Mayor Dan Mathieson told CTV Kitchener that a call to police prompted them to ask theatregoers to leave the Festival Theatre, where more than 1,800 had gathered Monday night to watch “The Tempest.” The festival’s Avon theatre was also evacuated.

Stratford Police Acting Deputy Chief Sam Theocharis later told reporters that a threat had been made over the phone at approximately 6:45 p.m.

“(Police) received a telephone call from an unknown individual advising us that there was an explosive set somewhere on the property of the Stratford Festival, at which time we contacted security at both theatres, which initiated their action plan for evacuation,” Theocharis said.

Police officers were searching the building and it was unclear how long the search would take, Theocharis added.

“The building is so massive and has so many small rooms, nooks and crannies,” he said.

“We want to make sure that public safety comes first and we have to make sure that the entire building is completely searched,” he added.

Artistic Director Antoni Cimolino insisted that the show will go on, as early as Tuesday. He said that ticketholders for Monday’s performance will get a refund or be allowed to reschedule.

“This is a sad, sad situation that this is taking place right now,” Cimolino told reporters.

“We’re hoping that we find out that this was in fact some kind of hoax, but we can’t determine that at the moment,” he added.

With a report from CTV Kitchener

Police have blocked off the road leading to @stratfest theatre. Hundreds evacuated after an apparent threat. Tonight is opening night. pic.twitter.com/Yu9mQdwgC7 — Tina Yazdani (@TinaYazdani) May 28, 2018

@SPSmediaoffice is at the Festival theater after a threat was received to the property. Both the Avon theater and the Festival have been evacuated as a precaution. Officers are on scene. Please stay away from the festival and upper queens and in the area of the Avon theater. — Stratford Police Service (@SPSmediaoffice) May 28, 2018