So was the shooter moving quickly from one concealment place to another, so he would not be pinned down and so he could engage new targets? He did eventually find himself in a corner where he was pinned down and finally taken out, but unfortunately he did a lot of damage first.
Being military trained, he realized that stationary shooters get flanked very quickly. That is why you shoot and move. To keep from being flanked. It is how he was able to shoot so many white officers. He fired shots, the police converged on the spot where shots were fired, but he wasn’t there. He had moved someplace else. Then shot again. Not only a sound tactic for maximizing killing, but makes it appear like multiple shooters and that forces police to delay and divide their resources.
Thing is, he was held by police in the garage for hours, so if there truly was a 2nd shooter, there would have been shots fired while the pinned down guy was engaged. There wasn’t any shooting and killing from other places after the perp was contained in a corner of the garage. So you can logically conclude there was only 1 shooter.