Man lying on sidewalk clubbed with bike lock

A man was left critically injured after a suspect allegedly clobbered him with a bicycle lock as the man was lying on a sidewalk in San Francisco’s Richmond District early Tuesday morning, police said.

Officers responded around 5:50 a.m. to the 4000 block of California Street near Second Avenue for a report of an aggravated assault, according to police.

There, officers determined the 55-year-old man had been struck while lying on the sidewalk. The victim was taken to a hospital with life-threatening injuries, police said.

The suspect, whose description was not immediately available, fled the scene and remains at large.