WASHINGTON — If you see emergency vehicles and people fleeing Dulles International Airport Saturday, officials say you shouldn’t be alarmed.

The airport said in a news release that it is holding an emergency exercise on Oct. 29 from 11 p.m. to 4:30 a.m.

A portion of the arrivals (baggage claim) level inside the Main Terminal will be closed to the public but there will be “little direct impact to passengers,” the release said. Flights and services will continue as scheduled during the exercise.

Airport staff and first responders from surrounding jurisdictions will participate in the exercise. Volunteers will play the roles of victims fleeing an incident and seeking assistance.

Emergency vehicles will be on the roadway outside the terminal until the exercise finishes.