Four terminals at Los Angeles International Airport (search) were shut down for more than three hours Saturday after a passenger bypassed security at one terminal and two flashlight batteries exploded during screening at another, authorities said.

The incidents, about a half-hour apart, were apparently unrelated and there was no link to terrorism, according to the federal Transportation Security Administration (search). Thousands of Labor Day weekend travelers were evacuated from the terminals.

The airport's main road, the Tom Bradley International Terminal and terminals 6, 7 and 8 were reopened around noon.

The scare at the international terminal came when batteries in a plastic flashlight inside checked luggage exploded as the bag was being hand-searched by a TSA worker, TSA spokeswoman Amy Von Walter said. She said the small but loud blast appeared to have been caused by old batteries.

The TSA worker suffered swollen hands and was taken to a hospital. Several other people complained of ringing in their ears.

The passenger whose bag was being screened at the time is a Japanese citizen who planned to take a flight to Tokyo, said Police Chief William Bratton. He was questioned by police and the FBI (search) before being released. The FBI also interviewed other nearby travelers. The flashlight in his bag disintegrated when the two C batteries inside exploded, Bratton said.

About half an hour earlier, security workers spotted a passenger bypassing security at United Airlines' Terminal 8 by running up a down escalator, TSA spokeswoman Jennifer Marty said. Security officials ordered the evacuation of the terminal and two connected terminals in order to re-screen passengers.

After about 40 minutes, security officials gave up searching for the passenger, who had gotten off a plane and went back into a secure area, said Larry Fetters, the airport's TSA security director.

"He probably remembered that he forgot his sunglasses in the area and went back to get it," said Fetters, adding that such incidents were not unusual nationwide.

About 220 flights out of 1,800 were delayed because of the security concerns, said Hal Jackson, an airport spokesman.

About 125,000 passengers normally pass through the airport on a busy travel day like Saturday, said Kim Day, acting executive director of Los Angeles World Airports.

"I'm not upset that we have to wait. It's better to err on the side of safety," said Katie Rao of Los Angeles, who played a card game with her husband as they waited for a delayed flight to Chicago.

Authorities are especially wary of terrorism at Los Angeles International Airport, among the world's busiest. It has twice been targeted for attacks -- a foiled bomb plot planned for around New Year's Day 2000, and a shooting at a check-in counter that left three dead on July 4, 2002.