PHOENIX -- Phoenix police said they shot a man who crashed his car into the back of another vehicle early Saturday and then nearly ran over an officer as he tried to escape.

The 20-year-old man was driving a Nissan Frontier on the Interstate 17 frontage road at high speed when officers saw him rear-end another vehicle near 27th Avenue and Camelback Road, Detective Cindy Scott said.

Police pulled up behind the Nissan, but the man repeatedly backed into a cruiser and then forward into the vehicle he had hit in an effort to ram his way free, Scott said.

Police opened fire when he drove at an officer. "At this time, the suspect was shot several times by officers," Scott said.

The victim is in critical condition and will be booked on two aggravated assault charges if he survives.