Updated at 7 p.m.: Revised to include latest number of delayed flights.

An early morning fire alarm forced an evacuation of Dallas Love Field’s terminal Friday, affecting hundreds of flights and scrambling plans for both airlines and passengers on one of the busiest travel days of the holiday season.

The alarm was triggered at the city-owned airport around 4:30 a.m. after a motor in an air conditioning unit overheated, burning wiring and a filter that resulted in smoke, airport officials said.

Dallas Fire-Rescue responders were able to address the issue in about 20 minutes, but the fire alarm still forced an evacuation of the entire terminal and passengers had to be re-screened at security checkpoints.

{"type":"video","title":"Dallas News Video","author_name":"Dallas News","_id":"FzZThyZDE6j-hoXFn4eT9QQ0_UJmHDgE","provider_name":"Ooyala","html":"

","raw":"{\"type\":\"video\",\"title\":\"Dallas News Video\",\"author_name\":\"Dallas News\",\"_id\":\"FzZThyZDE6j-hoXFn4eT9QQ0_UJmHDgE\",\"provider_name\":\"Ooyala\",\"html\":\"\\u003Cdiv class=\\\"oo-vid-container\\\" data-oo-content-id=\\\"FzZThyZDE6j-hoXFn4eT9QQ0_UJmHDgE\\\"\\u003E\\u003C\\/div\\u003E\\u003Cscript defer src=\\\"https:\\/\\/www.dallasnews.com\\/resources\\/motif\\/dist\\/js\\/ooyala.js\\\"\\u003E\\u003C\\/script\\u003E\"}","providerType":"ooyala","providerLink":"https://www.dallasnews.com/oembed","embedType":"video"}

The disruption led to security line waits of an hour or more as people filtered back into the terminal, but operations returned to normal by mid-morning, airport officials said.

At least 166 flights departing or arriving at Love Field were delayed as of Friday evening, according to flight tracking service FlightAware, with three reported cancellations. The airport, home to the nation's largest domestic carrier, Southwest Airlines, typically sees about 200 departures per day.

An airport spokesman said about 17,500 travelers were booked to depart from Love Field on Friday.

Vic Matchett arrived at the airport at 5 a.m. to a scene he described as “chaos,” with hundreds of people lined up waiting to get through the checkpoint.

His Southwest Airlines flight to Fort Lauderdale was initially supposed to depart at 7:25 a.m., but didn’t leave until 2½ hours later, causing him to miss his connecting flight to Grand Cayman, where he was planning to meet up with his wife.

“It’s not going to happen,” Matchett said about his connection as he waited at Love Field.

Southwest, the airport’s largest carrier with about 180 daily flights, did hold its flights to and from the airport from 6 to 7 a.m. to give affected passengers a chance to make it back through security.

But delays in Dallas were expected to have spillover effects across the carrier’s network, something the company said it was working to mitigate.

“We experienced delays for departing and arriving customers as passengers were rescreened by the TSA,” Southwest said in a statement. “Our ground operations teams are working with impacted customers to get them to their destinations safely and as quick as possible."

Across Southwest’s network, there were 1,049 reported flight delays, representing about one out of every four Southwest flights, although not all of those are attributable to the disruption at Love Field.

“There may be sporadic delays,” said travel industry analyst Henry Harteveldt, founder of Atmosphere Research Group. “It’s going to be inconvenient but not anything catastrophic.”

The good news for travelers is that any continuing effects will be resolved by Saturday morning, as Southwest’s network resets overnight.

The Dallas-based carrier advised passengers to check their flight status for the latest information before arriving at the airport.

Taking only 30 minutes to go through TSA lines now! Great work @TSA!!! All operations are completely back to normal in the terminal. pic.twitter.com/phkIAoDi1K — Dallas Love Field (@DallasLoveField) December 22, 2017

More scenes from Love Field where people have been allowed back in. @DallasLoveField says it is resuming normal operations. pic.twitter.com/eTUbuvmHU5 — Claire Cardona (@clairezcardona) December 22, 2017

Staff writer Tom Steele contributed to this report.