A standoff Thursday morning at SFO between multiple San Francisco police officers and an agitated man allegedly armed with two guns disrupted BART service and created a disruption at the airport's International Terminal, and ended with the man fatally shot.

The situation began unfolding at 7:30 a.m., with reports of an armed man at the entrance separating the SFO BART station and the Main Hall of the International Terminal. SFO spokesperson Doug Yakel put out a statement saying that arriving SFPD officers "attempted to de-escalate the situation, but the suspect continued to demonstrate threatening behavior." Officers are said to have "engaged non-lethal measures to neutralize the threat, but the individual continued to advance." An unknown number of shots were then fired, and initially the subject was reported to be alive but wounded.

Shortly thereafter, authorities said the suspect had died from his injuries.

A bystander was also reportedly hit by a bullet, possibly a ricochet, and was taken to a hospital for treatment of non-life-threatening injuries.*

Yakel told KPIX that a TSA employee was the first to call attention to the suspect. "This really began with a TSA employee that noticed an individual that was displaying some behavior that was concerning, and we always preach the mantra of, ‘If you see something, say something’ to report suspicious behavior,” Yakel said. “That TSA officer did exactly what we expected him to do, reported some behavior that didn’t look right and got the right resources there to address the situation."

An SFPD spokesperson has said that police do not believe the suspect intended any act of terrorism. And they said that the entire incident unfolded over about 45 minutes.

The suspect has not yet been identified, and has been described as a man in his 20s, about 5-foot-7-inches and 150 pounds.

As the Chronicle reports, San Mateo County District Attorney Steve Wagstaffe has announced that his office will be investigating the shooting. As you may know, while the SFPD provides security at the airport, it remains in the jurisdiction of San Mateo County.

Luis, a concierge for Air Canada, described a scary situation to the Chronicle of arriving at the BART station at 7:30 a.m. as he headed to work. He reported seeing five SFPD officers with guns drawn, yelling at BART passengers to "go back" — and Luis says he helped herd everyone on the BART platform back toward the other station exit at the other end of the platform, telling them there was a "shooter."

Airport operations were reportedly not impacted significantly, according to Yakel. However the Chronicle reports that a TSA checkpoint near the confrontation was closed, and air travelers were redirected to another checkpoint.

Air travelers using BART, however, experienced more disruption, being re-routed to Millbrae and then needing to find transportation back to the airport. Some BART trains were also reportedly canceled.

BART service resumed around 9 a.m., and SFO Station reopened as well.

BART issued a statement to ABC News saying, "The entire incident happened in the terminal. It didn’t happen at BART. It was near the entrance of our station but not at our station."

The SFPD and airport personnel were giving a media briefing starting at 12:30 p.m., and we'll bring you any new details as we get them.

Update: California Attorney General Rob Bonta says his office will be conducting its own independent investigation of the shooting.

*This post has been corrected to show that the bystander hit by a bullet required hospital treatment.