SAN FRANCISCO (CBS SF) — A stabbing following an argument in San Francisco’s Tenderloin neighborhood late Monday night left one man with life-threatening injuries and also injured a second man who had tried to intervene, according to police.

The stabbing was reported shortly after 11:25 p.m. in the 300 block of Leavenworth Street.

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The suspect fled after the stabbing and had not been arrested as of Tuesday morning, and police did not immediately release a detailed description of him besides saying he is in his mid 30s.

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The victim who intervened is expected to survive his injuries, and there was not any other information available on the condition of the other man who suffered life-threatening injuries.

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Anyone with information about the stabbing is asked to call the Police Department’s anonymous tip line at (415) 575-4444 or to send a tip by text message to TIP411 with “SFPD” at the start of the message.