Southwest Airlines is asking travelers to arrive at least two hours before their scheduled departures as technical issues are forcing it to check-in customers manually.

At Los Angeles International Airport, several dozen people crowded the Southwest terminal, waiting to be issued hand-written tickets. The Dallas-based company Sunday afternoon that about 300 of the 3,600 flights set to operate for the day had been affected by delays so far.

The long lines at check-in may mean some passengers didn’t make their flights.

Emily Mitnick, who was flying to Detroit from Denver International Airport, said she missed her 10 a.m. flight, even though she parked her car around 8 a.m. She estimated that about 1,000 people were online at the check-in for a boarding pass. When she went downstairs to the curb-side check-in, she said there were about a couple hundred people in line there as well.

By the time she got on line to go through security, it was around 10:15 a.m.

“The clock was ticking and the flight took off,” said Mitnick, who was trying to get to Detroit through a different flight to Chicago.

In a statement on its website, the airline said the technology issues are affecting its website and mobile app, as well as its reservation centers and airport check-in systems. It said that while it is working on the technology issues, workers at airports are helping customers with their itineraries.

Representatives for Southwest did not immediately respond to messages seeking more details Sunday.

Photo Credit: Soutwest's recently rebranded checkin counters. Southwest Airlines