WASHINGTON (AP) — Homeland Security Secretary Alejandro Mayorkas says people traveling for Memorial Day weekend should be patient because there will be long lines at U.S. airports.

The Transportation Security Administration has been in a hiring surge so it can be ready for increased travel this weekend and over the summer as the nation emerges from the coronavirus pandemic, Mayorkas told ABC's "Good Morning America" on Friday.

"People will see lines because there's going to be a tremendous amount of people traveling this weekend," Mayorkas said. "Patience is required."

Also required are masks, he added.

"The mask mandate is a federal mandate in airports and on airplanes," he said. "That's going to hold true probably until mid-September."

Airline executives say domestic leisure travel is at pre-pandemic levels, and the number of people passing through U.S. airports daily is likely to top 2 million before the week is over — the first time that has happened since early March 2020.