A man sustained life-threatening injuries Sunday night when he was struck by a car while crossing a west Santa Rosa street, police said.

The man, described only as being in his 50s, was hit at about 7:15 p.m. on Marlow Road, just south of the Guerneville road intersection, Sgt. Rich Celli said.

The man was not at a crosswalk. The area was dark and not directly lit by street lights.

He was hit by a man driving a dark Lexus sedan northbound on Marlow. His identity was not immediately available.

Celli said the driver was cooperative and submitted to a voluntary alcohol test, although he did not appear to have been drinking.

There was evidence the driver tried to avoid the crash, Celli said.

"I believe those are skid marks," said Celli, pointing to the rear of the car.

The victim was transported to Santa Rosa Memorial Hospital. Some of the injured man's clothing and a shoe were illuminated by red flares and emergency lights.

Celli said the injured man had been carrying a bottle of alcohol. Witnesses said he may have been a homeless man who frequented the area.

Ken Watson, a cashier at a nearby Circle K convenience store, said he heard a sound like an impact, ran out of the store and saw a motionless body in the middle of the street.

He thought it was a man named Charles who lived with another man and a woman under a Fulton Road bridge.