1 Dead, 6 Missing After Fire at 19th Century Stone Building in Montreal: 'Heartbreaking Tragedy'

At least 1 person is dead with 6 others missing following a building fire in Montreal, which broke out Thursday morning and left several people injured, Montreal Police share.

The fire, which took place in the historic Old Montreal district and inside the three-story building, left the 15-unit stone structure engulfed in flames and prompted a search within the rubble for seven missing people believed to be trapped, per multiple reports. Nine other people were injured in the blaze, according to local station CP24.

The Canadian Press/Alamy Live News Building fire pictured in Montreal

When reached for comment, Montreal Police (Service de police de la Ville de Montréal) confirmed to PEOPLE that one person had been found dead of the seven missing. "The deceased has not been identified yet," the spokesperson shared. "From what we know as of now, there are six other persons missing. The investigation is ongoing, for the missing and the cause of the fire."

A spokesperson for the Montreal fire department, Service de securite incendie de Montreal, referred PEOPLE to the Montreal Police.

More than 100 firefighters worked to contain the blaze, fire department spokesperson Marie-Eve Beausoleil told Reuters. The building, located at the intersection of Place d'Youville and St-Nicolas Street, housed long-term and short-term rentals, such as Airbnb. City officials said, per the outlet, that the residential building units were not intended to be rented through services like Airbnb given municipal rules.

The Canadian Press/Alamy Live News Building fire pictured in Montreal

The fire's cause remains unknown, with no known connection between the short-term rental units and the fire.

"Our hearts go out to the victims of this tragedy, and to their families and loved ones. We are providing our support to those affected, and we are assisting law enforcement as they investigate. We are also engaged with the mayor's office," Nathan Rotman, Airbnb's Regional Policy Lead, Canada, told PEOPLE in a statement.

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Montreal Fire Operations Chief Martin Guilbault said at a news conference Saturday night, per CP24, that the building would be slowly dismantled beginning Sunday morning, and that various sources led them to believe that "there may be victims inside the debris." As CBC reports, demolition crews began to tear down the building's top two floors Sunday.

"We want to announce tonight that we're gonna take down this building slowly, stone-by-stone, to make sure that the environment inside here is safe for all the people from the fire department and the police department to do their work," Guilbault said.

The Canadian Press/Alamy Live News Investigators and firefighters pictured in Montreal

The first known victim's body was recovered from the rubble at 6:45 p.m. Sunday, Steve Belzil, commander of the Montreal police arson squad, revealed at the news conference. "The steps to identify this victim will be taken by our partners in the forensic scientific laboratory," Belzil said.

"Our goal is for the investigation to advance in order to provide answers for the families affected," Belzil added.

In a Monday report from the Montreal Gazette, Montreal Police Inspector David Shane said drones and a bucket truck were used to locate the first victim — with the six other people suspected to be inside the building being from Quebec, Ontario and the U.S.

"The result of the different steps we took in the investigation point out that these people who are still missing are probably in the rubble, unfortunately," Shane said. "We worked with the [building] owner, we worked with cyber investigation, we looked at social media, we looked at cellphones, and when we add all this information together, everything stopped the night of the fire."

Despite reports that some of the rooms in the 19th century building didn't have windows, Guilbault said it's too early to know that or if the building had functioning fire alarms. "For now, we cannot confirm anything about the way the building was made, and we don't have any specific information about no windows in some apartments, we have to confirm that," he said.

As Shane told the Gazette Monday, "police and firemen and women will not give up until we've explored all the rubble and obtained as much information possible for the families."

Montreal Mayor Valérie Plante tweeted on Saturday that the fire is a "heartbreaking tragedy."

"Our priority is to support the families of the victims who are still waiting for answers at the present time," she wrote. "We are closely following the investigation carried out by the [Montreal Police], which will shed light on this drama."