POSTED: Friday, March 9, 2012 - 1:15pm
UPDATED: Friday, March 9, 2012 - 1:19pm
NBC NATIONAL NEWS — Pennsylania police are still working to determine the identity of the gunman who opened fire inside the Western Psychiatric Institute on Thursday.
Several people were shot inside of the hospital's lobby.
Two people were killed, including the gunman.
Seven other people were injured, including a University of Pittsburgh police officer who was grazed in the leg by a bullet.
Investigators said the injured officer and two other officers saved several lives after shooting and killing the gunman during exchanged gunfire.
Five victims remained in the hospital Friday morning.
Two other victims were released from the hospital Thursday evening.
Police ran fingerprint tests on the gunman, but were unable to find a match.
Investigators said the man did not have any identification on him.
Police said they believe the gunman acted alone and used two semi-automatic handguns in the shooting spree.
According to authorities, he walked into the lobby of the hospital around 1:40 p.m. and began shooting.