Police have released new details about a ‘chain-reaction collision” in Vaughan that left a 72-year-old woman dead.

The collision happened on Pine Valley Drive north of Major Mackenzie Drive at around 7:30 p.m.

In a news release issued on Friday, police said that officers have since learned that the driver of a blue Mazda CX-3 stopped their vehicle in the roadway in order to allow a dog to cross.

The Ford Escape operated by the 72-year-old victim then came to a stop behind the Mazda, police say.

That is when it was struck truck by a southbound Mercedes, causing the chain-reaction collision.

The 72-year-old was taken to hospital but was pronounced dead a short time later.

Police say that the occupants of the other two vehicles sustain only minor injuries. “Investigators are appealing to any witnesses who have not yet spoken with police, and to anyone who may have dashcam footage of the area around the time of the collision, to please come forward,” the news release states.