The province's anti-corruption squad said it was carrying out nine raids at the seat of the municipal government, in Old Montreal, and six other ones in different borough offices.
A news report said the new mayor, Michael Applebaum, and the man he recently replaced, Gerald Tremblay, were both among 25 people questioned by police. Spokespeople at the police squad and city hall did not confirm, or deny, that report.
Applebaum added some details later, at a 9:15 p.m. news scrum outside city hall. He confirmed meeting with police but said he was not a target of the probe — only a participant.
"I'm not under investigation," Applebaum said.
"I'm there to work with the police."
He did not elaborate on reports that the raids were related to the 2009 campaign financing of Union Montreal — the long-ruling, now-crumbling municipal party Applebaum recently abandoned. He said he wanted to avoid revealing details that might hamper the investigation.
But the mayor did say: "I ran a clean campaign. I raised money legally."
He also sought to downplay Tuesday's events, calling it "normal" that so many officers would be involved in a probe of this kind and that he would speak with them.
These latest raids were part of a two-year-old investigation related to fraud, breach of trust, and falsified documents in Quebec.
A number of arrests have already been made in connection with construction corruption, which is also the subject of an ongoing public inquiry.
A note went out to city employees explaining the situation.
"Due to exceptional circumstances, we are asking you to leave your work stations and to immediately exit Montreal city hall," said the email.
"This order stands until further notice."
One municipal politician described the scene inside city hall.
Richard Bergeron, leader of the Projet Montreal party, said he was supposed to have a meeting with the mayor at 4:15 p.m.
But suddenly a voice on the loudspeaker ordered everyone to leave the building.
As police officers moved in, city officials moved out. Employees received an email that the building was closed until further notice, and city hall was locked down.
While no arrests were expected Tuesday, more than 20 witnesses were scheduled to meet with investigators.
More than 125 police officers were participating in the various operations.
One of those raids was being conducted in Cote-des-Neiges-NDG — the borough governed for years by Applebaum, who is currently the interim mayor of Montreal.
Applebaum was chosen by council to lead a coalition government after the previous mayor, Tremblay, resigned in scandal last fall.
He became the city's first Anglo mayor in a century. An election will be held later this year.
The main opposition leader, Louise Harel, summed up the situation: "I've never seen anything like this," she said outside city hall.
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