JACKSONVILLE, Ark. » Guards at a sprawling Air Force base in Arkansas perceived a threat when they shot and critically wounded a man who crashed his SUV near an entrance and got out of the vehicle holding a rifle, the base commander said.

But authorities have not released the identity of the man or said why they think he tried to drive Monday onto Little Rock Air Force Base, which is about 15 miles northeast of its namesake city.

Two guards stationed at the base’s main gate shot the man, who was a civilian, base commander Col. Charles Brown Jr. told reporters. He said it wasn’t immediately clear whether the man fired his weapon, how many shots were fired or if the man exchanged words with the two guards.

"We do feel the threat has been mitigated. There is no additional threat to the Little Rock Air Force Base," Brown said during a Monday afternoon news conference near the main gate.

The base issued a statement earlier Monday saying the man was hospitalized in critical condition. A person described as a bystander was treated and released for "unrelated medical care," though no details about the person or the injuries were released.

Brown said it was unclear why the man wanted to get on the base, which is a major C-130 training facility and home to more than 8,000 active-duty military personnel and civilian employees. The C-130, an aircraft with a roughly 129-foot wingspan capable of carrying more than 40,000 pounds, is used to move troops and equipment into hostile areas.

The incident was reported around 9:15 a.m. near the main gate along busy U.S. 67 in Jacksonville, the city that abuts the base. Heavily armed security personnel quickly sealed off access to the base, and the main gate wasn’t reopened until late Monday afternoon.

Brown said traffic that time of day is usually heavy enough that it would have been difficult for the man to speed up to the gate.

The commander said as the SUV approached, it hit and jumped a curb and knocked over a street sign. He said the man, whom Brown only described as white, then started to get out of the vehicle while holding a rifle.

"It appears he may have lost control of the vehicle," Brown said.

No one from the base was injured, and investigators were interviewing the guards, Brown said. Jacksonville Police Sgt. Dustin Brown also had no information about the man.

The FBI is offering assistance during the investigation, according to Deb Green, a spokeswoman for the Little Rock FBI office. She declined further comment.

A bomb squad could be seen checking an SUV parked near a curb and sidewalk outside a visitor center at the base’s main gate Monday afternoon. All four of its doors, along with its tailgate, were opened, and officials told those standing nearby to take cover behind other vehicles as workers wearing ordnance-disposal gear approached the vehicle.

Associated Press writer Allen Reed contributed to this report from Little Rock.