San Francisco Police Chief Greg Suhr described injured officer Adam Shaw's wound as a bullet hole that went clear through his bicep. The bullet has not been recovered.
The man arrested in this incident is 50-year old Jeffrey Ruano. He is now in police custody. But, he hasn't been charged with shooting an officer because authorities didn't find a gun on him.
Detectives are trying to rule out the chances that Shaw might have been shot by his partner, because the only bullet casings found at the scene are from guns carried by San Francisco police officers.
"Whether or not we will ever know definitively that the shot came from his partner, until we can recover the round that went through his arm and match it ballistically to the partner's gun, we don't know that," said Suhr.
Shaw is a six year veteran, but as of Monday afternoon, he has not been formally interviewed; so detectives have not determined if he saw the suspect pull a gun. It is not known whether Shaw fired his gun, and how many times.
That information could help account for all the bullet casings found at the scene, help rule out an accidental shot by his partner or a ricochet from Shaw's own weapon.
As for Ruano, he did have ammunition for a handgun on him.
"Under no circumstance did he want to be apprehended by police. That said, we do not have any evidence that he possessed a firearm and we don't have an admission from him that he did," said Suhr.
Ruano is under arrest for outstanding warrants and is charged with using his Mustang convertible as a weapon after he attempted to run down Officer Shaw.