A window washer plummeted to his death from the 18th storey of a downtown skyscraper Tuesday afternoon.

He fell onto a platform of the Blue Cross building at the corner on President-Kennedy Ave. and Aylmer St. at 1:30 p.m.

The worker, who was employed by Mon laveur de vitres, was tethered to a metal washing platform when it became dislodged and plummeted onto another roof, two storeys up, above the Maison du Jazz restaurant on Aylmer. He had been yanked off the roof of the Blue Cross building.

"I was working inside the restaurant and we heard a big bang, so I came outside," said John Henry, an employee at Maison du Jazz. He said he heard screaming and a call for help from two other employees.

Henry called 911 and climbed on the roof to help.

"I took his pulse to see if he was still (alive), and he was not breathing anymore. He had big beams, big metal beams on him that fell down with him," said Henry.

Other employees said the victim, a man in his 40s, was a veteran window washer with decades of experience.

The CSST is launching an investigation into the incident, but it is too soon to speak with witnesses who are still shaken up from the fall, said Julie Melan�on, a spokesperson for the CSST.

This is the fourth incident since 2000 in which a window washer has fallen from a building, said Melan�on, adding that this is the second fatal fall.