Airport security officials are investigating today how a carry-on bag — which had tripped an alarm after being swabbed for explosives and weapons— was picked up by the passenger and disappeared before it could be searched.Depending on what surveillance records show, the security breach could mean disciplinary action or termination for an employee, said Sidney Hayakawa, Transportation Security Administration security director in Honolulu.

“If the person was asleep, absolutely,” Hayakawa said. “But if someone was busy and made a mistake, we’ll correct that... we need to identify the weaknesses they had and correct the weaknesses.”

Several thousand passengers were evacuated from the main and interisland terminals at about 6:30 a.m., Hayakawa said.

Security units and search dogs combed the terminals until about 9:30 a.m., when the rescreening process began, said Rod Haraga, state transportation director.Passengers were allowed back into the terminals for rescreening beginning at 7:30 a.m., but the incident had already caused a domino effect of flight delays.

The suspicious bag never turned up in the second screening, so the assumption is the test was a false positive, Hayakawa said.

Haraga said a test swab of the passenger’s carry-on bag indicated traces of TNT explosives, but officials acknowledged that different substances can mimic the same result..

Interisland passengers line up on the street outside the ticket lobby today after a security scare emptied the Honolulu International Airport terminal. Richard Ambo • The Honolulu Advertiser

Passenger Carole Friesen from Alberta, Canada, said she arrived at the interisland terminal at 7 a.m. to check in and found a sea of people waiting along the roadside at the baggage check-in area.

"My flight from Canada to here had delays for numerous reasons, so this is just icing on the cake," said Friesen, who was still waiting outside the terminal at 9 a.m. for her Big Island flight.

Hawaiian Airlines spokesman Keoni Wagner said the shutdown affected four of its interisland flights, delaying each about 20 to 30 minutes. Aloha Airlines spokesman Stu Glauberman said all of its morning flights were delayed, with one Maui round-trip flight cancelled because "it was running way too late."

Hayakawa said this morning's airport shutdown and the federal officials' decision to raise the national terrorism threat level to "orange," indicating a "high risk of terrorist attacks, were unrelated.