An Aurora police officer was clinging to life late Sunday after he was ejected from his patrol car and severely injured when he tried to avoid a car that had stopped in front of him as he was responding to a call with his lights and siren activated.

The crash happened near the intersection of Sixth Avenue and Norfolk Street in Aurora.

Witnesses said the officer had to swerve suddenly to avoid the car that stopped in front of him in his lane of traffic. The patrol car rolled several times and the officer was ejected from the vehicle.

It was not known how fast it was traveling.

The officer was flown by Flight for Life to Swedish Medical Center with what were believed to be serious head injuries.

The officer’s identity was not released.

The vehicle that stopped in front of the officer left the scene and police were trying to locate it Sunday night.

Aurora Police Chief Daniel Oates and several other Aurora police officers were at Swedish Medical Center late Sunday night.