The morning calm at Joint Base San Antonio-Lackland was shattered Friday when an apparent murder-suicide at a classroom building left two men dead, triggered a lockdown and brought a swarm of military, federal and local law enforcement.

Now, a shaken military community Lackland is trying to piece together what may have prompted the violence led one man to shoot another man, before turning the his Glock pistol on himself.

"This morning, we received one of those calls that you never want to receive," Brig. Gen. Bob LaBrutta, the commander of the 502nd Air Base Wing and Joint Base San Antonio, said in a news conference at the base after the lockdown had been lifted. "Our hearts and prayers go out to the families that are going to be affected by this tragedy. The care of those families is really foremost in our minds right now."

Details about the incident were slow to emerge Friday. LaBrutta said that, pending notification of the victims' families, the Air Force would not release any information about them, on the deceased pending notification of their next of kin, their relationship, or speculate about the shooting's possible motive in the shooting.

However, An initial internal Pentagon communication obtained by Air Force Times obtained an internal Pentagon memo indicating said the commanding officer of a training squadron at the base was shot by another airman. That communication, distributed among senior military officials as law enforcement officials swarmed the base's Medina Annex, apparently listed an incorrect squadron. The mistake was pointed out by an Air Force spokeswoman at the Pentagon, who said she was not authorized to offer further clarity.

The Associated Press also reported Friday afternoon that an unnamed senior U.S. official confirmed said an airman shot his commander.

The shooting took place at Building 147 of the Medina Annex, in a classroom facility known as Forbes Hall, said Lt. Col. Bobby Ford, who leads the base's 802nd security forces squadron commander at Lackland, said at the news conference. The first 911 call reporting the active shooting was made to 911 at 8:40 a.m. Central Standard Time, he added Ford said.

Ford said two patrols responded to the scene within three minutes of the call being placed and entered the building to begin searching. The base was also immediately placed on lockdown, he said. 

Within eight minutes, Ford said, that officers found the two men dead in an office on the first floor. LaBrutta said two Glock pistols were found at the scene. 

For the next hour, first responders continued to sweep the building to searching for other potential shooters or victims until 9:59 a.m. At 10 a.m., the building was declared safe and law enforcement began investigating the crime scene, Ford said.

The lockdown was lifted at 10:17 a.m., Ford said.

Bexar County Sheriff's Office spokesman James Keith told reporters that "Right now it does appear to be a murder-suicide situation."

Lt. Col. Jeremy Waller, commander of the Office of Special Investigations' 11th Field Investigations Squadron at Joint Base San Antonio, said OSI agents are conducting the crime scene investigation and looking into how the shooting began. Waller said the investigation would continue for several hours.

The FBI said its agents were offering assistance to support the investigation. Terrorism is not suspected, officials said.

Friday's But the shooting marks the latest in a series of violent attacks inside the nation's military facilities. The trend has caused anxiety among service members and their families, while sparking debate over how the military can ensure their safety and comes as at a time of high tensions and concerns about troops' vulnerability to mass shootings in the United States.

Last summer, after In June 2013, an Army captain was shot and wounded by her estranged husband at Joint Base San Antonio-Fort Sam Houston. In 2015, four Marines and a Navy sailor were killed by a terrorist in Chattanooga, Tennessee, there were calls in Congress and beyond to allow military personnel to carry firearms while on duty. That debate has intensified as And in 2009, 13 people were killed and more than 30 were wounded in a mass shooting at Fort Hood in Texas. And as the United States has ramped up its war against the Islamic State militant group in the Middle East, ISIS sympathizers have issues threats against U.S. troops and their families, encouraging sympathizers to attack them in the open on social media, further raising fears.

The Lackland shooting also took place on the same day several hundred new airmen graduated from had their basic military training at the base graduation ceremony.

LaBrutta said only authorized law enforcement such as security forces and Office of Special Investigations agents are allowed to carry weapons on base. He said the investigation into Friday's shooting will look at how the weapons were brought into the facility.

The incident shooting also took place on the same day that several hundred new airmen and their families gathered at the base to mark their graduation from had their basic military training at the base graduation ceremony.

Phillip Swarts of Air Force Times and David Larter of Navy Times contributed to this report.

Two people are dead in an apparent murder-suicide at Joint Base San Antonio-Lackland in Texas, the Bexar County Sheriff's Office said Friday morning.

Shortly before noon Eastern Standard Time, the sheriff's office said the situation is contained and that the shooter is no longer active. The base issued a release saying there are no indications the shooting was a terrorist attack.

In a news conference at the base, Brig. Gen. Bob LaBrutta, the commander of the 502nd Air Base Wing and Joint Base San Antonio, said two men were found dead in an office on the first floor of building 147 of the Medina Annex, a classroom facility known as Forbes Hall. Two Glock weapons were found at the scene, LaBrutta said.

"This morning, we received one of those calls that you never want to receive," LaBrutta said.

According to initial internal Pentagon communications obtained by Air Force Times, the commanding officer of a training squadron at the base was shot by an airman. The initial communication may have listed an incorrect squadron.

An Air Force spokeswoman at the Pentagon could not immediately confirm the internal report. LaBrutta said the Air Force will not release any information on the deceased pending notification of their next of kin, or a possible motive in the shooting.

The Associated Press reported Friday afternoon that an unnamed senior U.S. official said an airman shot his commander.

Lackland called the sheriff's office about the shooter at about 8:40 a.m. Central Standard Time, and the base was placed on lockdown. LaBrutta said the lockdown was lifted at 10:17 a.m. local time.

"They did find two people who were dead," Bexar County Sheriff's Office spokesman James Keith told reporters. "Right now it does appear to be a murder-suicide situation."

OSI is investigating the shooting, and the FBI has offered its assistance.