Shots were fired Wednesday in Fort Hood, Texas. Four people died, including the gunman and leaving 16 others injured.

The gunman, active duty soldier Ivan Lopez, 34, carried a .45-caliber Smith and Wesson semi-automatic pistol, officials said. Lopez served in Iraq during a one year tour and a former Army National Guardsman stationed in Puerto Rico. An investigation on Lopez’s background at Fort Hood and previous confrontations are not yet confirmed.

Those who were injured were taken to Darnell Army Hospital and Scott & White Memorial Hospital. During a hearing, hospital officials told reporters those caught in crossfire had wounds to the chest, necks, abdomens and their extremities. Three patients were in critical condition and in ICU, while five are in serious condition.

The last shooting at Fort Hood occurred in 2009, where 13 people was killed.

President Barack Obama gave a speech Wednesday evening, saying “we’re going to get to the bottom of exactly what happened. Obviously that sense of safety has been broken once again.”

As the night persisted and law enforcement raised the base off lockdown, military personnel released information to reporters.

Lt. General Mark Milley, of Fort Hood, said in a press conference “the attack occurred in multiple units. The shooter got into a vehicle, fired shots from the vehicle and walked into another building and opened fire again. There is no indication that this incident is related to terrorism.”

Milley told reporters, the shooter was diagnosed with PTSD.

Defense Secretary Chuck Hagel said, “We will continue to address the issue.”