San Francisco police opened fire on a knife-wielding man in a wheelchair in an incident caught on citizen cell phone video.

The man in the wheelchair, who apparently survived the shooting, did not appear to be much of a threat to police – although there were reports that he had stabbed an officer beforehand.

In fact, if you look closely at the video, he appears to have his hands in the air as the cops move in with their guns drawn.

Then he turns his back to the officers as they begin firing their guns. At least one officer fired a non-lethal beanbag gun and another officer fired a lethal service revolver.

I couldn’t really see it in the video, but KTVU reports that he had tossed the knife seconds before he was shot.

The incident occurred Tuesday in front of a mental health facility. Police said the man was slashing tires. He also was not confined to the wheelchair, even though he was sitting in it.

San Francisco police said they would rather have pumped him with 50,000 volts of electricity rather than lead bullets, but they unfortunately do not carry Tasers.

Now there are four separate investigations into the incident, including from the San Francisco homicide unit, internal affairs, the district attorney’s office and the office of citizens’ complaints.

The obvious question is; why didn’t police shoot him after he had stabbed an officer instead of waiting until he was no longer a threat?