Operations at Los Angeles International Airport were returning to normal this afternoon following Friday’s shooting that killed a TSA officer and closed parts of the airport.

Airport officials said today that LAX’s Terminal 3 had reopened. Officials urged travelers who left belongings behind in the shooting’s aftermath to work with their airline to claim possessions.

Thousands of fliers across the U.S. were delayed after the closed parts of the airport. The prolonged shutdown at the nation’s third-largest airport was particularly troublesome for those hoping to head to the East Coast or across the Pacific Ocean.

About 1,550 flights with 167,000 passengers were affected, airport spokeswoman Nancy Castles said in a statement today.

Of those, 724 were scheduled arrivals with an estimated 67,850 passengers and 826 were departures with an estimated 99,200 passengers on board.

The situation was improving. Daniel Baker, CEO of flight tracking site FlightAware, said in an email today that there were “no notable delays” and 28 cancellations related to the LAX shooting.

After Friday’s shooting, flights bound for Los Angeles that had not yet taken off were held at their gates for hours by the Federal Aviation Administration. The so-called ground stop lasted several hours. Some flights already in the air were allowed to land at LAX, while others diverted to nearby airports. Some passengers who landed at LAX after the shooting spent at least two hours sitting on planes parked in a remote corner of the airport.

The ripple effect was felt across the country.

Tasi Lua arrived at LAX after the shooting Friday, but was unable to board his flight to Denver. He found a corner in Terminal 2, plugged in his laptop and cellphone and slept on the floor.

“I’m used to traveling, and things happening. It wasn’t too bad,” said the 25-year-old. “I could see other people who weren’t taking it as well.”

Even though the airport never fully closed, travelers trying to fly out were unable to reach it because of massive road closures.

Gina Marie Lindsey, executive director of Los Angeles World Airports, which operates the Los Angeles airport, said it will take “quite a deal of time” to get operations back to normal. She said it will be a “carefully orchestrated logistical ballet.”

LAX’s Terminal 3, where the shooting occurred, was closed Saturday morning as the forensics investigation continued. Only the ticket counter and parking structure were open.

A man carrying a note that said he wanted to “kill TSA” pulled a semi-automatic rifle from a bag around 9:20 a.m. local time and shot his way past a security checkpoint. One Transportation Security Administration officer was killed, authorities said.

One security expert doubted much could be done to prevent similar incidents.

“I am not sure what can be done other than effectively banning most types of guns as in the U.K. where there are minimal shootings,” said Kenneth J. Button, a public policy professor and director of the Center for Transportation, Policy, Operations and Logistics at George Mason University.

“This could just as well happened on a street in New York or at a shopping mall,” Button said in an email in which he also alluded to last year’s mass shootings in a Colorado movie theater and at a Connecticut elementary school. He added that “airports are possibly one of the safest places given the security there.”

Los Angles is a major gateway for flights to Asia, Australia and New Zealand. Domestically, the largest cities served are San Francisco, Las Vegas, New York, San Jose, California, San Diego and Phoenix.

However, it is not a major connection point such as Chicago, Atlanta, Dallas and Minneapolis.

Most airlines issued waivers for people traveling through Los Angeles, allowing them to change flights without paying a fee.

JetBlue diverted flights from Boston, New York and Fort Lauderdale, Florida, to nearby Long Beach airport. Southwest Airlines diverted at least one flight — a trip from Chicago that landed in Denver.

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AP Business Writer Barbara Ortutay contributed to this story from New York.