TORONTO -- A woman believed to be in her 70s has been transported to hospital with life-threatening injuries and three other people have been injured after a van and a TTC bus collided in North York on Monday evening.

Emergency crews were called to Yonge Street and Finch Avenue at around 6:45 p.m. for a collision.

Toronto police said the van crashed into the bus.

A woman in her 70s was transported to a trauma centre with life-threatening injuries, Toronto paramedic services said.

Paramedics later said that a man was also taken to a trauma centre with serious injuries and that two other people were transported to local hospitals with minor injuries.

It is not yet clear what caused the collision.

The intersection has been shut down as police investigate the collision.