Travelers struggled with hours-long security lines at some airports as officials warned of Transportation Security Administration staffing shortages amid the partial government shutdown.

Houston’s William P. Hobby Airport told customers Sunday to arrive as early as 5 hours before their flights, and warned that security wait times could exceed three hours.

The partial government shutdown has meant that TSA officers are working but without regular paychecks.

TSA callouts rose during the 2018-2019 government shutdown, prompting the closure of some checkpoints and leading to longer screening lines. It ended hours after a shortfall of air traffic controllers curtailed flights on the East Coast. The current shutdown, however, is affecting only Department of Homeland Security employees, including TSA officers.

Hartsfield-Jackson Atlanta International Airport, the world’s busiest, as well as Louis Armstrong New Orleans International Airport, said travelers should arrive at least 3 hours early because of the disruptions.