Local and federal officials will run a large-scale homeland security drill Tuesday near the Vincent Thomas Bridge.

The Coast Guard warned passersby not to be surprised if they see helicopters or even hear what sounds like gunfire. Police and fire crews will be practicing how they’d respond to a threat at the ports of Los Angeles and Long Beach, according to a news release.

“Boaters and the public may notice increased law enforcement activity within the port, including helicopters in the sky, vehicles, vessels, sirens, blue lights, blank fire and flash bangs in the area,” authorities said in the release.

The drill will run from 9 a.m. to 2 p.m., according to the news release.

It will include the Coast Guard, FBI, Los Angeles Port Police, Los Angeles Police Department, Los Angeles Sheriff’s Department, Los Angeles Fire Department, Long Beach Police Department and Long Beach Fire Department.

Authorities said they don’t expect the drill to impact any commercial traffic at the port, but vessels and people are barred from the area near the Vincent Thomas Bridge between 9 a.m. and 3 p.m. Tuesday.

Anyone who needs more information can contact the Captain of the Port at 310-521-3801, the Coast Guard said.