Federal authorities are leading the investigation into the shooting, which is being treated as a hate crime.
The suspect surrendered to the police after being barricaded in the building and was taken to the hospital.
According to law enforcement officials, the suspect has been identified as Robert D. Bowers, 46.
Four police officers were among the injured and were taken to three hospitals.
US President Donald Trump in a tweet about the incident said, “Events in Pittsburgh are far more devastating than originally thought. Spoke with Mayor and Governor to inform them that the Federal Government has been, and will be, with them all the way.”
Later Trump told reporters that the killings might have been prevented if there had been an armed guard in the building. “If they had some kind of a protection inside the temple maybe it could have been a much more different situation, they didn’t.”