Sean Eckford reports: "Ottawa shocked"

The gunman arrived at the city's main bus station with a high-powered rifle shortly before rush hour on Tuesday and opened fire in a storage room, police said.

One witness told how the gunman roamed through the building, firing at random at staff until his rifle jammed.

He then spent several hours locked in the building, sealed off and surrounded by police, before shooting himself.

Police take cover from the gunman

Two men have been taken to hospital suffering from bullet wounds.

Around 100 workers were in the immediate area of the shooting - a huge depot housing about 500 buses.

Investigators say they do not know if the gunman shot at random or deliberately targeted his victims.

But the Canadian Broadcasting Company says there are reports he went in looking for his former supervisor.

Other reports said he was a long-time bus driver who was laid-off, went back to work, then quit a few months ago.

'Sick individual'

The authorities have not yet named the gunman, but members of the transit workers union identified the dead man as a former member of staff.

"He had a long history of mental illness," said Paul Macdonell, president of the Amalgamated Transit Union.

"He's been off on sick leave and back and forth. The company's given him lots of breaks and finally he quit.

"This is just a very sick individual."

Sylvain Couture, a mechanic, said he saw the gunman shoot two people inside the stockroom.

"He was coming here to make some trouble. He lost it," added Mr Couture.

Strict gun laws

The shooting has shocked Ottawa. Mass murders are rare in Canada, which typically has fewer than a 1,000 murders a year.

Gun ownership is highly regulated in Canada and last year the government brought in tough new controls.

They include a ban on most semi-automatic rifles and mandatory registration for all guns - something that had previously only applied to handguns.