A four-week-old baby and another child were rushed to hospital following a crash on Highway 401 Tuesday afternoon.

Ontario Provincial Police said a car containing two children and a female driver collided with a tractor-trailer on Highway 401, east of Port Union, around 1:30 p.m.

A four-week-old baby was rushed to a Toronto hospital with life-threatening injuries.

Another child was also taken to hospital with critical injuries, said OPP spokesperson Const. Linda Wolf.

A woman, believed to be in her 30s, was treated at the scene and released to accompany the children, Wolf said.

Wolf said that both the car and the truck were using the transfer lane to get into the collector lane when the collision occurred.

The car lost control, hit a guard rail and went into the truck’s path. The truck tried to avoid the car, but was not able to do so, said Wolf.

Wet, rainy conditions at the time may have contributed to the crash.

“We’re looking at weather conditions as a possible factor,” said Wolf.

Portions of the eastbound lanes of Highway 401 were closed near Port Union as police investigated the collision.

Wolf said the closure was expected to continue through the evening rush hour.

“Both the 401 and the collector lane are moving, but at a slow pace,” she said.