Los Angeles ? A gunman opened fire Thursday at the ticket counter of Israel’s El Al airlines at Los Angeles International Airport, killing one person before being shot dead by an airline security guard, police said.

The shootout happened with security on high alert around the country for a possible terrorist attack on July Fourth.

There was no immediate indication the shooting was tied to terrorism, a senior Bush administration official said, though he added he could not rule it out. Administration and law enforcement officials were trying to determine the shooter’s identity, the official said, speaking on condition of anonymity.

At least one other person was transported by ambulance after the shootout at the Tom Bradley International Terminal.

After the shooting, much of the airport was closed off and thousands of people were evacuated.

Shortly before noon, the gunman approached someone at the terminal and opened fire, police said. Byron Tucker, a spokesman for Gov. Gray Davis, confirmed that an El Al security guard fatally shot the gunman.

The guard survived the shooting, police said.

A witness, Thad Weimlein, described an initial flurry of fire, followed by silence, then more gunfire.

In a cellphone interview with CNN, Weimlein said he saw plainclothes policemen pulling out their guns and badges at the same time.

At first, “a lot of people thought it was fireworks and a prank,” Weimlein told CNN. “It was probably eight to 10 shots. People were hitting the floor.”

FBI agents were at the scene, but investigators had no immediate indication of the shooter’s identity, nationality or motive.

Two people being questioned but were not considered suspects, police said.

At least five ambulances were at the airport. Traffic was stopped on the roadway for departing passengers but moving steadily along the roadway serving arrivals.

Fire officials deployed a team to check for hazardous materials.

El Al, based in Israel, is known as one of the most security-conscious airlines in the world.