UPDATE -- 11:00 p.m. ET: Via the AP:
A Fort Hood official says the shooter in the attack at the Army base was being assessed for whether he had PTSD.
Lt. Gen. Mark A. Milley said Wednesday that four people were killed including the shooter and 16 others were wounded in the attack. He says the wounded were all military members.
Milley says there is no indication the shooting was related to terrorism.
He says the shooter is married and served in Iraq 2011.
Milley also revealed that the shooter used a .45 caliber handgun.
UPDATE -- 9:20 p.m. ET: Rep. Michael McCaul (R-Texas), Chairman of the House Committee on Homeland Security, told CNN four people have been killed in the Fort Hood shooting, including the shooter. He says he has been briefed on the situation and the information comes from state and federal agencies.
McCaul -- as well as several news organizations -- also identified the shooting suspect as 34-year-old soldier Ivan Lopez, though it has not been independently confirmed.
The shooting is being described as a "soldier-on-soldier" incident, but terrorism hasn't been entirely ruled out, according to CNN.
Two U.S. law enforcement officials confirmed to The Associated Press that four people -- including the shooter -- have been killed in the shooting at Fort Hood and another 14 are injured.
UPDATE: The Associated Press is reporting the Fort Hood shooter has died of a self-inflicted wound, citing a Justice Department internal report.
There have been reports of a possible second shooter, but no confirmation.
NBC later reported the shooter's death as well:
A senior defense official confirmed one person is dead and 14 have been injured in Fort Hood shooting, according to the Associated Press.
A military police officer stops a car at Fort Hood, Texas, after a shooting on the Army base Wednesday, April 2, 2014. One person was killed and at least 14 injured in a shooting Wednesday at Fort Hood. (AP Photo/Austin American-Statesman, Deborah Cannon)
In Chicago, President Barack Obama vowed that investigators will get to the bottom of the shooting, seeking to reassure the nation whose sense of security once again has been shaken by mass violence.
In a hastily arranged statement, Obama said he and his team were following the situation closely but that details about what happened at the sprawling Army post were still fluid. He said the shooting brought back painful memories of the 2009, when 13 were killed at the same post in the deadliest attack on a domestic military installation in history.
Obama reflected on the sacrifices that troops stationed at Fort Hood have made - including during multiple tours to Iraq and Afghanistan. He called the situation "heartbreaking."
"They serve with valor, they serve with distinction and when they're at their home base, they need to feel safe," Obama said. "We don't yet know what happened tonight, but obviously that sense of safety has been broken once again."
At least one person has been killed in a shooting at Fort Hood in Texas, KWTX-TV reports. Police are reportedly searching two possible shooters.
There have been reports that as many as eight people have been injured, but the Bell County Sheriff's Office told TheBlaze that four people have been injured at Fort Hood and there is an active shooter situation.
A Fort Hood witness said Wednesday that soldiers were escorting men, women and children at gunpoint from a building, WWBT-TV reports.
Following reports of a shooting at the Fort Hood, the Army base issued an order Wednesday for everyone on site to “shelter in place.” The alert was issued on the base’s Twitter and Facebook pages.
"Injuries are being reported. Be AWARE!! If you are in the Ft. Hood Post area there is an on-going active shooter," the Waco Police Department tweeted on Wednesday.
CNN aired footage that reportedly shows the scene at Ft. Hood:
The 1st Calvary Division, which is based at Fort Hood, sent a Twitter alert telling people on base to close doors and stay away from windows.
There were unconfirmed reports of multiple injuries from a possible shooting at Fort Hood, according to KCEN-TV.
The suspect was believed to still be at large Wednesday afternoon.
The base was the scene of a mass shooting in 2009. Thirteen people were killed and more than 30 wounded in what was the deadliest attack on a domestic military installation in history.
As TheBlaze reported on Monday, the FBI issued an alert regarding a manhunt for a recent Army recruit who authorities believed had plans for a “Fort Hood-inspired jihad against U.S. soldier.
The source of the information in the alert was listed as an “FBI agent,” Fox News reported. The alert said:
“On 20 March 2014, the Kansas City Division FBI became aware of an individual named BOOKER aka Muhammad Abdullah Hassan who had publicly stated his intention to commit jihad, bidding farewell to his friends and making comments indicating his jihad was imminent. BOOKER had been recruited by the US Army in Kansas City, Mo., in February 2014 and was scheduled to report for Basic Training on 7 April 2014. Kansas City Division Agents interviewed BOOKER on 20 March 2014.”
There was no indication that the reported shooting at Fort Hood Wednesday is related to terrorism. Further, CNN's sources say the shooting has nothing to do with the FBI alert.
Stay tuned to TheBlaze for future updates on this breaking story.
See below for how the event unfolded live:
The Associated Press contributed to this report. TheBlaze's Oliver Darcy contributed early breaking developments to this story.