A faulty circuit breaker caused an explosion in Rosemont that triggered a shutdown on the metro’s blue line for a large portion of Thursday afternoon.

Six successive explosions underground sent smoke billowing up through a utility hole at the corner of Belanger and St-Andre St. at about 12:30 p.m.

“It’s the first time I saw something like that,” said Lina Garcia, who shot footage of the incident as it happened.

The explosions occurred after some equipment underground caught fire, according to Hydro-Quebec.

Firefighters quickly evacuated nearby buildings, including the courier company where Garcia works.

“We had to leave everything behind,” said Garcia.

Electricity was cut to the area as a precaution. As a result, the blue line was out of service until 4:30 p.m. and the STM implemented a shuttle service.

Diesel generators will be used

Hydro Quebec said on Friday that until it can repair the problem, ten diesel generators will be set up to power the buildings that would otherwise have no electricity.

“When there's an outage to the infrastructure, that's critical. The metro, it's a priority number one for us to re-establish the service,” said Hydro-Quebec spokesperson Jonathon Cote.

“The problem is that since there was a fire and the fire department had to intervene, there was only so much we could do. What we did is we tried to reconnect as many people as possible through other power lines in the other area, but there was no way unfortunately that we could reconnect the metro at that time,” he added.

Hydro Quebec said the explosion was caused when a circuit breaker failed.

"The circuit breaker is going have to to be replaced. This is a much bigger intervention so that's not going to be fully completed today," said Cote.

“This is very serious for us… we don' t want something like that to happen again. So we're going to look at what happened exactly, what equipment was involved, is there any equipment like that could be problematic. Definitely we're going to have to look at this and make sure that everything else is secure,” said Cote.

Later in the day an emergency generator being used in a seniors' residence caught fire, forcing the evacuation of the building.

Hydro-Quebec said that at its peak, 21,000 clients were without power. About 500 homes were still without electricity at 7 a.m. Friday, but they were all restored by the afternoon.

No one was injured.