SAN FRANCISCO (CBS SF) – A man was found critically injured after an apparent attack near Market and Mason streets in San Francisco on Tuesday evening.

The 49-year-old victim was found half-conscious in the street and possibly having a seizure about 7:30 p.m., police said.

He was taken to San Francisco General Hospital with head trauma that is considered life-threatening, according to police.

A half-dozen suspects allegedly involved in the attack fled the scene and had not been found as of Wednesday morning, police said.

No other information about the case was immediately available. Anyone with information is asked to call the Police Department’s anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411 with “SFPD” in the message.

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