The investigation into a possible drive-by shooting at a Mission District homeless encampment Tuesday night is hitting a dead end after witnesses to the incident stopped cooperating with police.

San Francisco Police Department spokesperson Officer Grace Gatpandan says that a 43-year-old woman was shot at around 6 p.m. Tuesday while in the area beneath where the on and off ramps to Highway 101 converge over the 2800 block of Cesar Chavez Street.

That area is well-known as a place where homeless people set up camp, Gatpandan says.

Reporting witnesses said that six male suspects and a black sedan were spotted at the scene during the shooting, but refused to provide further information, Gatpandan says.

The victim was transported to San Francisco General Hospital with a non-life-threatening gunshot wound to the thigh.

Investigators are still trying to determine a motive for the shooting, Gatpandan says, noting that it's still unclear if this was a drive-by shooting or if the shooter was on foot. It certainly doesn't help that witnesses are keeping mum, so Gatpandan urges anyone with any information on the shooting to call SFPD's Anonymous Tip Line at 415-575-4444 or to text a tip to Tip411 with SFPD at the beginning of the message.