Meanwhile, protesters in front of the White House burned an American flag
From CNN's Jim Acosta and Betsy Klein
A protest group set an American flag on fire at Lafayette Park across from the White House.
Secret Service officers quickly extinguished the flames and detained several people.
A press release from a protest group announced plans to set a US flag alight, and noted that protester, Gregory “Joey” Johnson and members of the Revolution Club and the Revolution Tour were demonstrating against President Trump and his "Salute to America" event.
It is not known if Johnson was one of those being held by police.
Trump was scheduled to speak at the Fourth of July event at 6:30 p.m. ET today, but the event has been delayed (Note: We're not sure how long the delay will last.)
5:12 p.m. ET, July 4, 2019
Tonight's event is delayed, but Trump still plans on speaking at it
From CNN's Jim Acosta
President Trump still plans to deliver remarks at his "Salute to America" event tonight, despite an announcement there would be a delay in the program.
Trump was originally scheduled to deliver an address at 6:30 p.m. ET.
White House press secretary Stephanie Grisham said there has not been a bad weather call and added that the President would travel the short distance to the Lincoln Memorial.
What we know so far: We don't have details about the length of the delay, but there is severe weather in the Washington area and low cloud cover.
4:45 p.m. ET, July 4, 2019
National Park Service funds will foot part of Trump's Fourth of July bill
The Post said the use of the funds was confirmed by two unnamed individuals familiar with the agreement.
The paper, which said administration officials "have consistently refused to say how much" the event will cost, noted that former National Park Service deputy director Denis P. Galvin said that typically, the July 4 celebration on the mall comes at a cost of about $2 million for the agency. According to the Post, the $2.5 million redirected by the park service "represent just a fraction of the extra costs the government faces" for the event.
Citing budget documents, the paper also said the nearly $2.5 million from the agency "amounts to nearly 5 percent of the funds that less-profitable parks used last year for upgrades."
Could cross a campaign line: According to the Post, Brendan Fischer, the federal reform director for the Campaign Legal Center, said the President's speech could cause issues related to the use of the NPS funds as "federal appropriations law prohibits using public money for political purposes."
If Trump "refers to some of the 2020 presidential hopefuls, or polling related to the race, Trump's reelection campaign may be required to reimburse the U.S. Treasury," the paper said.
"'The content of the event, and the nature of the event, is probably the determining factor,' as opposed to donors getting to see Trump up close," Fischer told the Post, referring to the the fact that the President's political allies received some of the VIP tickets to the celebration.
4:06 p.m. ET, July 4, 2019
Trump's political allies received VIP tickets to the show
From CNN's Kevin Liptak and Sarah Westwood
President Trump's political allies received some of the VIP tickets to today's Fourth of July spectacle on the National Mall, according to people familiar with the event.
While the public will be able to view the event from afar, the areas closest to Lincoln Memorial, where Trump will speak, are reserved for ticket holders.
The White House has declined to say how the tickets will be allocated, or even how many will be given out. An official said only that "VIPs, friends and family, and members of the military" are getting access to the cordoned-off area.
But at least some of those with the special access appear to be Trump's political boosters.
The "Salute to America" will occur on the National Mall rather than the White House, which is where presidents have celebrated the Fourth of July in the past.
Tickets required: The Secret Service said in a statement last week it was responsible for securing the area closest to the Lincoln Memorial during the event.
"Tickets are required for this event and individuals will be required to undergo an additional level of security screening to include magnetometers," the agency said.
3:38 p.m. ET, July 4, 2019
900 members of DC National Guard have been activated for the celebration
From CNN's Barbara Starr
The DC National Guard has activated 900 members to provide traffic control and security on the streets and in the Metro subway system in Washington, DC, according to a military official.
However, the number is nearly triple the typical 300-person activation for the Fourth of July because of the need to have additional personnel for President Trump’s event.
More people are expected to be on the streets as a result of the Fourth of July celebration. They'll be traveling through the subway system, which is a larger footprint for security teams to cover, the official said.
2:12 p.m. ET, July 4, 2019
Why the National Park Service won't say how many people will attend Trump's event tonight
From CNN's Betsy Klein
While President Trump is setting the bar for large crowds on the National Mall tonight, it’s worth noting that the National Park Service will never provide a crowd count for the festivities.
“The Committee has provided no funding for crowd counting activities associated with gatherings held on federal property in Washington, D.C. If event organizers wish to have an estimate on the number of people participating in their event, then those organizers should hire a private sector firm to conduct the count.”
The backstory: The provision came to be following the 1995 Million Man March, when Louis Farrakhan threatened to sue the National Park Service for estimating the crowd at 400,000, according to Jason Alderman, who wrote it as an aide to then-Rep. Sidney Yates.
“At a time when national parks were woefully underfunded with billions of dollars in deferred maintenance (sadly little has changed 20 years later) it felt like a particularly poor use of taxpayer money to have the Park Service count crowds at events on the National Mall,” Alderman wrote in the Huffington Post in 2017, adding, “I was simply motivated to free the Park Service from being a political punching bag and allow them to divert those resources spent on counting to instead be used for improving the parks under their care.”
1:51 p.m. ET, July 4, 2019
Fourth of July celebrations continue: Here's what is still to come in D.C.
The National Independence Day parade just wrapped up in Washington D.C., but there are still a lot of festivities to come.
Here's a look at what you can expect to happen tonight:
"Salute to America" at the Lincoln Memorial: This event was a new addition to the itinerary by President Trump this year. It will start at 6:30 p.m. ET and feature a speech from the president.
What else you will see: Trump confirmed to reporters that there will be tanks and other armored vehicles on display for the "Salute to America" event. Military officials told CNN the tanks will not parade along Pennsylvania Avenue. The Navy's elite airshow squadron the Blue Angels will do a flyover and will be joined by other aircraft, including the helicopter and 737.
"A Capitol Fourth:" This annual free concert, hosted by John Stamos, will start at 8:00 p.m. ET on the west lawn of the Capitol Building.
About the fireworks: Due to Trump's event, the launch site for the DC fireworks show was moved from the reflecting pool in front of the Lincoln Memorial to West Potomac park, along the Potomac river. The DC fireworks show, televised on PBS, will run a full 35 minutes and wrap at 9:42 p.m. ET.
Protests are planned: The National Park Service granted a permit for a protest less than a mile from the Lincoln Memorial that will include a large inflatable balloon in the likeness of Trump as a baby. Anti-Trump veterans will hand out T-shirts for the USS John McCain in order to troll Trump, who has belittled the dead senator and former prisoner of war.
1:48 p.m. ET, July 4, 2019
2020 Democratic presidential candidates react to Trump's Fourth of July celebration
Democratic presidential hopefuls are reacting to President Trump's Fourth of July celebration plans on the campaign trail today.
Here's what they're saying:
In Storm Lake, Iowa, Mayor Pete Buttigieg told CNN: “Reducing our nation to tanks and shows of muscle just makes us look like the kind off loud mouth guy at the bar instead of the extremely diverse and energetic nation that we are.”
In Slater, Iowa, Sen. Bernie Sanders said: "I think we need money to go into affordable housing. I think we need money to go into rebuilding our infrastructure. I'm not quite sure that we need money to go into put tanks in downtown Washington, DC, frankly."
1:43 p.m. ET, July 4, 2019
This is what it looks like at the National Mall today
Crowds started gathering at the National Mall ahead of President Trump's "Salute to America" event tonight.
There was a sculpture depicting Trump holding a cell phone while on a toilet.