The Baltimore-Washington International Thurgood Marshall Airport suspended security checkpoints temporarily Monday morning due to a law enforcement investigation.

Screening at security checkpoints A, B and C were briefly suspended after 8 a.m. “due to a law enforcement investigation,” the airport said in a post on social media.

Screenings resumed at about 8:30 a.m. after law enforcement gave the all-clear, said BWI spokesperson Jonathan Dean. The investigation determined there was no threat, Dean said.

“We thank passengers for their patience and cooperation,” he said.

Transportation Security Administration and BWI officials didn’t respond to questions about what triggered the investigation.

Hundreds of domestic and international flights come and go from BWI every day, and about 27 million passengers travel through the airport each year. The pause comes amid the busy holiday travel season, which can already cause longer lines and wait times.