A 42-year-old woman and four-year-old girl are dead as a result of a multi-vehicle collision in Markham this morning.

The crash happened at around 9:45 a.m. in the area of 16th and Bur Oak avenues and involved a black Toyota sedan heading east and a black Infinity travelling west.

According to York Regional Police, the woman and young girl -- mother and child -- were located inside the Toyota. The woman, who was found without vital signs, was rushed to a hospital in Markham where she later succumbed to her injuries, police said.

The young girl was airlifted to SickKids Hospital via ORNGE air ambulance but succumbed to her injuries as well.

Workers at a nearby construction site told CP24 they rushed to the scene after hearing the collision and attempted CPR before emergency services arrived.

Inside the Infinity, police located a man and a baby. The man was initially unconscious and was taken to hospital with serious but non-life-threatening injuries. Police said his child appeared to be unharmed but was taken to hospital as a precaution.

"We heard a big bang, we didn't know what it was, so we came to the back of the house," a construction worker said at the scene. "We just come across the street. We see the two cars piled up over here."

The Major Collision Bureau has been called in to investigate the circumstances leading up to the crash.

Police are urging anyone who was in the area at the time and may have witnessed the incident to come forward.

“What we need now is for people to come forward and offer any information on what did take place here," York police Const. Andy Pattenden said.

Roads were shut down in the area while police investigated the crash, but they have since reopened.

Anyone with information can contact the York Regional Police's Major Collision Investigation Unit at 1-866-876-5423.

With files from Joshua Freeman.