A 14-year-old boy suffered life-threatening injuries after he and his older sister were struck by a driver in Milton Tuesday evening.

The woman, 23, is in "serious but stable" condition in hospital, Halton police said in a statement.

The pair were using the crosswalk at the corner of Thompson Road and McCuaig Drive shortly before 7 p.m. when they were hit.

The driver, a 27-year-old woman from Milton, was heading southbound in a sedan when she collided with the pedestrians. She struck another vehicle before coming to a stop. Neither person travelling in the second vehicle were hurt, police said.

The driver who struck the woman and teen boy was taken to hospital for minor injuries and released.

Police did not indicate whether she could face legal repercussions.

Halton Regional Police's collision reconstruction unit is heading up the investigation.