D.C.’s July 4th fireworks will have “TSA-style” security, won’t start until 11 p.m.

This year’s Fourth of July celebrations in Washington, D.C. — marking the nation’s 250th birthday — will include hours of military flyovers and a massive fireworks display that could stretch late into the night, with some of the tightest security in decades, officials said Monday.

This Fourth will include “the largest display of fireworks our city has ever seen,” D.C. Metropolitan Police Department Interim Chief Jeff Carroll said at a news conference. Usually the fireworks begin at around 9 p.m., but this year, they are expected to begin at 11 p.m. and are “going to be longer than in previous years, we are told,” Mayor Muriel Bowser told reporters.

President Trump has said he plans to speak at 9 p.m., ahead of the fireworks. Starting at 1:15 p.m., hundreds of planes will participate in a “Fourth of July Airshow,” the president said. The National Mall also is hosting a daily event called the Great American State Fair that will run until July 10, and some local neighborhoods are hosting parades and other events on the Fourth.

The main festivities have been deemed a National Special Security Event, a designation used for massive events like Super Bowls and presidential inaugurations. Security measures will be more extensive than for any Fourth of July event in D.C. since shortly after the 9/11 attacks, Carroll said, with more blocking vehicles, more fencing, concrete barriers and other security measures that aren’t employed for a typical Fourth of July celebration.

The FBI isn’t tracking any credible threats to the Fourth of July, but “we always remain vigilant,” said Darren Cox, assistant director in charge of the FBI’s Washington field office.

Those planning to view the fireworks show from the Washington Monument grounds should expect “TSA-style” security, with magnetometers screening guests, according to Tara McLeese, special agent in charge of the Secret Service’s Washington field office.

Guests can arrive as early as 1 p.m., and should enter on the east side of the Washington Monument at Constitution Avenue and 14th St. NW, or at Independence Avenue and 14th Street SW, McLeese said.

McLeese said each guest in the restricted area is allowed only one clear bag no larger than a gallon, or a small clutch purse. There will be no storage for prohibited items.

The capacity of the primary viewing area at the Washington Monument is set at about 150,000, according to Secret Service Special Agent in Charge David Yamen, who runs the agency’s dignitary protective division. It is expected to hit capacity.

Attendees of the Great American State Fair at the National Mall are encouraged to remain there to watch the fireworks show, rather than attempting to enter the primary viewing zone on the Washington Monument grounds, said Scott Brecht, chief of the U.S. Park Police. Leaving one zone and moving to another will require additional security screenings, and reentry may not be possible.

To get to the National Mall on the Fourth, public transit use is encouraged. The D.C. Metro will be free after 5 p.m., Washington Metropolitan Area Transit Authority General Manager Randy Clarke said, “to really make sure people can not only enjoy the festivities all over the region as a community, but also make sure from a safety point of view we can get people going through.”

“If you’re going downtown for the fireworks, plan ahead, be ready for an increased security presence, crowds, and road closures,” D.C. Homeland Security and Emergency Management Agency Director Clint Osborn said. “I would say that if you’re going downtown and you’ve done this before, don’t assume you know what it’s going to look like.”

Join CBS for “The Great American Block Party 250,” a primetime special on Saturday, July 4, hosted by CBS Evening News anchor Tony Dokoupil and Entertainment Tonight’s Nischelle Turner, featuring live musical performances, celebrations around the country, and the largest fireworks show in history in the skies over the nation’s capital. Tune in July 4 at 8 p.m. ET on CBS and stream it on Paramount+ and CBS News 24/7.