A driver was critically injured Friday afternoon after colliding with a Nassau County ambulance that was en route to an emergency at the time.

The three-vehicle accident happened on Old Country Road in Westbury, Nassau County Police said.

The ambulance and second car struck each other before the two then crashed into a third car, police said.

The medic is in stable condition at a local hospital, but the civilian driver’s injuries are critical, according to officials.

The driver of the third car declined medical attention, police said.

It’s unclear what caused the accident, and no charges have been filed, police said Friday night.