The Toronto Transit Commission is defending the bus driver who hit a utility worker who ended up dying Thursday night.

One man died and another was taken to hospital after a TTC bus plowed into the mechanical arm of their maintenance vehicle. (Tony Smyth/CBC)

The 50-year-old woman was driving a southbound No. 7 bus on Bathurst Street when it slammed into the 42-year-old man in the underpass just north of Dupont Avenue.

The man, who was on the road acting as a safety spotter for a colleague doing maintenance work from the bucket lift of a utility truck, was pronounced dead at the scene.

TTC spokesman Brad Ross wouldn't say how much experience the driver has, but said she's well-trained.

"Our operators, our drivers … are highly trained, skilled professional drivers trained in defensive driving," Ross said Friday afternoon.

"We have almost 2,000 vehicles on the road every day, whether they're buses and streetcars, carrying almost one and a half million people around. Incidents unfortunately do happen."

It was the fourth accident involving the TTC since last week.

The Ontario Ministry of Labour and Toronto police are scrutinizing the latest incident.

Investigators say the maintenance workers, who are from a private company called Stacey Electric, might have positioned their truck in a way that caused the accident.

"The bucket was elevated in the air with a 51-year-old man," said Toronto police spokesman Tony Vella. "That bucket also had an arm which was sticking out onto the passing lane, with the result that when the bus was going through the passing lane, the TTC bus went through, hit the arm, causing the bucket to move."

The worker in the bucket lift was knocked down, but survived with non-life-threatening injuries. The bus driver is receiving counselling from the TTC.

None of the names of those involved in the accident has been released.