As usual... conflicting reports, and not enough information to say for sure what led up to the shooting.
Unfortunately most Philly news outlets have very loose standards when it comes to reporting incidents like this. You'll drive yourself crazy trying to get to the facts of the matter.
The two aspects that raise red flags for me, which are consistent across the reporting, are the officer's conduct after the shooting, and the point that Glenn brings up - why did he pursue Taylor into the home? If he truly believed that Taylor had pointed his pistol at him, why would he blindly pursue him into a house?