Two young siblings remain in critical condition after they were involved in a three-vehicle collision at the base on Yonge Street on Saturday afternoon.

Police say they were called to the intersection of Yonge Street and Lake Shore Boulevard just after 3:30 p.m.

At the scene, they found two minivans and a BMW that had been involved in a collision.

As a result of the collision, nine people were taken to hospital, including four children from the same family who were riding in a Dodge Caravan.

A three-month-old boy and his three-year-old sister were rushed to Sick Kids Hospital, where they remain in critical condition.

The three-month-old boy suffered head injuries and a broken leg, his three-year-old sister also suffered head injuries.

Police believe that the two seriously injured children were not wearing proper child restraints at the time of the collision -- and that the three-month-old boy was being held by his mother in the backseat of the Dodge Caravan.

The other two children in the Dodge Caravan, who were wearing child restraints, received only minor injuries in the collision.

It is believed that the Dodge Caravan driving north on Yonge Street when it was struck by a Chevrolet Uplander that was driving west across Lake Shore Boulevard.

Police say the Dodge Caravan then came to rest on the northwest corner of the intersection, while the Chevrolet Uplander struck the BMW which was stopped on Yonge Street and facing south.

Toronto police Sgt. Tim Burrows told ctvtoronto.ca that the intersection was closed for eight hours as investigators examined the collision scene.

"Seatbelts save lives," Burrows said. "Because of their design and what they're meant to do, they reduce injuries, they reduce the possibility of death and they keep you inside the vehicle where you are safest."

Police are asking anyone with information about the collision to call police at 416-808-1900, or to call Crime Stoppers at 416-222-8477. They can also provide tips online at www.222tips.com, or text TOR and their message to CRIMES (274637).