Los Angeles International Airport struggled this morning to return to normal after it was shut down for more than an hour so law enforcement could investigate what turned out to be false reports of gunfire, authorities said.

Twenty-seven flights were diverted to other airports but many had completed their trips to LAX by 1:25 a.m., according to LAX Public Relations Director Nancy Castle. About 280 flights were  delayed, including 120 arrivals and 161 departures. Two flights were cancelled, she said.

Airport staff were using audio and visual messages to keep  passengers apprised of flights and delays, said LAX Public Relations Director Nancy Castle. Concessions stayed open past closing time to serve passengers on delayed or diverted flights.

Traffic on the upper departure level was flowing smoothly but traffic on the lower arrival level was congested this morning, she said.

“Motorists picking up arriving passengers are advised to wait for free in the cell phone waiting lot at 96th Street and Vicksburg (Avenue) until their arriving passenger calls to say they are at terminal curbside ready for pickup,” Castle said.

Transportation Security Administration and Customs and Border Protection agents were continuing past the end of their shifts to screen passengers whose departure was delayed and those arriving for delayed flights, she said.

Law enforcement continued to investigate multiple 911 calls at 8:45 p.m. Sunday saying there was an active shooter in Terminal Eight, Assistant LAX police Chief Dave Maggard said before dawn this morning.

“Some reported hearing gunfire,” he noted.

As airport police checked Terminal Eight, there were reports of gunfire in other areas, Maggard said. The airport terminals were evacuated and roadways were shut down.

Officers and teams with bomb-detecting K-9s searched the terminal area but found no indication of an active shooter, he said.

Throughout the event, the public and passengers were kept informed of developments, and a new wireless emergency alert system passed information to cell phone customers within five miles of the airport, Maggard said.

“We are grateful it was not actually an active shooter,” he said.

Just prior to the report of gunfire, police detained a man dressed in as Zorro in black with a mask who witnesses feared had a sword, he said. Officers searched the man and found a plastic sword. Maggard said he did not know whether the sword incident and active shooter reports were related.

“We will continue to investigate throughout the day,” he said.

The news of possible gunshots prompted some people to rush out the wrong security doors, setting off alarms that added to the sense of danger, LAX police union head Marshall McClain said on KNX 1070 Newsradio.

McClain told the station some people inside the airport heard loud noises they knew weren’t gunshots, but said it was possible the noises induced some other people to call 911.

Following a intense search of the areas, an “all-clear” was issued about 9:50 p.m., but a logjam of vehicles and people stranded by the evacuations brought airport operations to a crawl and will require much of the night to untangle, McClain said.

“Report of shooting at LAX proven to be loud noises only,” Los Angeles police Capt. Andy Neiman said on Twitter. “No shots fired. No injuries.”

All passengers needed to be re-screened through airport security before returning to the terminal, authorities said.

“People evacuated from terminals are allowed back in as they pass through TSA screening,”  Badlissi said. “There should be an easing of the situation. Flights are still arriving but passengers should check the status of their flights.”

A passenger from Anaheim Hills named Mike said he and his wife were at a baggage claim area in Terminal 7 when they heard orders to evacuate and joined a rush of people crowding onto the sidewalk as uniformed personnel with assault rifles ran into the terminal.

“It was pretty scary,” he told KNX.

Departure and arrival roadways into the Central Terminal Area reopened at about 10:50 p.m. Sunday, LAX officials said.

Airport spokeswoman Mary Grady said it would take much of the night to bring traffic and pedestrian patterns back to normal.

The incident affected air traffic nationwide, as flights in and out of LAX from airports across the country were re-routed or canceled, McClain said.

Authorities will be vigilant in making sure the false alarm was not a diversion to create mayhem elsewhere at the airport, he said.