Update 4:42 p.m. CDT: An autopsy on the suspect is scheduled to be performed Friday, Harris County Medical Examiner spokeswoman Roxanne Mena told the International Business Times. Houston PD said it has no "identifying information" about the suspect, including his name.

Generally, it takes 48 hours after an autopsy for the medical examiner to determine a cause of death, Mena said. The medical examiner is also expected to use fingerprint comparisons and other information to identify the suspect.

As far as when a cause of death will be determined, "it's looking more like Monday," Mena said.

Update 4:28 p.m. CDT: The gunman has died of his injuries, according to the Houston Police Department. Gunfire was exchanged between the suspect and a U.S. Homeland Security Department officer, but a statement from the Houston PD is unclear as to whether the man died from a self-inflicted wound or from a shot fired by the officer. The medical examiner is expected to make that determination. From the Houston Police Department's Facebook post:

"The armed suspect in the airport incident has died from his injuries. He entered Terminal B and fired at least one shot in the air. A nearby Department of Homeland Security Officer heard the gunfire and immediately responded. The Homeland Security Officer and the suspect fired shots simultaneously. The suspect was struck and treated by responding paramedics who pronounced him dead in an ambulance. The Harris County Medical Examiner (Institute of Forensic Sciences) will determine the suspect’s cause of death.

"No other travelers in the terminal were hurt. The airport remains safe and the area of the terminal was quickly contained. The investigation remains ongoing."

Update 3:49 p.m. CDT: Eyewitness accounts of the shooting are coming in, including from an employee at a McDonald's at the airport who said she started running as soon as she heard the shots.

"As soon as [the man] walked in, he just automatically started shooting quickly," the employee, Kendra Carrizales, told KHOU. "And we hear two shots and we just automatically started running. We ran all the way to the back." 

Houston Airport passenger Grant Huff gave this video interview to Rebecca McCormick, a self-described syndicated travel journalist:

Houston PD said it would give more details on the incident shortly, and would be releasing any updates on its Facebook page.

A man was seriously wounded after shots were fired at Bush Intercontinental Airport in Houston on Thursday afternoon, a Houston Police Department spokesman told the International Business Times.

Police received calls about discharge of gunfire by the ticketing area at Terminal B at the Houston Airport at around 1:35 p.m. CDT Thursday, the spokesman said.

The man, who was not immediately identified, was transported to a local hospital with at least one gunshot wound that was considered life-threatening.

The spokesman did not confirm reports that the man was dead or that the gunshot wound was self-inflicted.

A man fired at least two shots from an AR-15 rifle, a Houston Police Department captain and a witness told KHOU. The shots did not hit anyone.

An air marshal then fired at the alleged gunman but did not strike him with any bullets, the news outlet reported.

The man then pulled out a handgun, shooting and killing himself, according to Reuters.

The incident prompted the FAA to issue a ground stop for all flights at the Houston Airport.

Witness Greg Newburn posted a series of tweets describing the incident.

“Shots fired at Houston airport holy f---. Holy f--- holy f---,” he wrote. “Shaking … Sorry for the profanity that was crazy.”

He said witnessing the shooting was “terrifying.”

“But it’s over now. I’m safe,” Newburn tweeted.