Two 13-year-old girls have been rushed to a trauma centre after being struck by a vehicle in front of a school in Agincourt Monday, Toronto police say.

One of the girls is in life-threatening condition, while the other is in serious condition, Toronto paramedics say.

Police were called to the scene in the area of Midland and Lockie avenues just before 3:30 p.m. for reports of a serious collision.

The girls had been walking east to west across a block on Midland Avenue, while the vehicle approached southbound, said Sgt. Edmund Wong of Toronto police's traffic services. The pair were struck as they crossed Lockie Avenue, he said.

The vehicle's windshield was cracked in the process.

Grade 10 student Adam Yang was waiting to cross the street when he saw the crash unfold. He said it didn't seem real at first.

"It was kind of a blur... I just froze," he said. Moments later, he called 911.

Both girls were Grade 7 students at Sir Alexander Mackenzie Senior Public School, Toronto District School Board spokesperson Ryan Bird said in a statement.

"Our thoughts are with the students and we are supporting their families in any way we can," Bird said, adding social work supports are available to students and staff.

Police say the female motorist involved stayed at the scene. It's not yet known if speed was a factor.

Roads in the area were closed for several hours while police investigated.