One man is in critical condition and two other people are injured after a welding explosion Tuesday afternoon in east-end Montreal.

The incident happened at 12:40 p.m. at Desy Mechanics at 9410 Notre Dame St. E in the Mercier neighbourhood.

A worker was welding a gas tank when the explosion occurred.

The Montreal police arson squad is on site to help the Quebec Workers’ Health and Safety Board in their investigation.

So far it is unclear why the tank exploded, or if there was gas in the tank during the welding operation.