Storms force evacuation at Washington's National Mall during Trump's July 4 celebration

President Donald Trump's plans to commemorate America's 250th anniversary of independence with a rally on the National Mall were disrupted Saturday by severe storms that gathered near Washington, forcing event organizers to order an evacuation.

"Freedom 250 will share updates on programming and doors reopening," a Freedom 250 spokesperson said in a statement, encouraging participants to seek shelter at museums and federal buildings near the National Mall. Washington's metro system also made several of its underground stations available for shelter.

The disruption was particularly acute in Washington, where signs at the Great American State Fair posted an alert shortly after 7 p.m. ET encouraging participants to leave the area. As the order to evacuate was played over loudspeakers on the National Mall, some people appeared to be standing in place while others were walking toward exits. National Guard troops told people to leave. The U.S. Secret Service announced it had temporarily closed checkpoints to screen attendees ahead of Trump's speech, which was scheduled to begin around 10 p.m. ET.

Plans for fireworks were still moving forward in other cities including Chicago and New York, where tall ships passed the Statue of Liberty earlier in the day, recalling the fanfare around America's 200th anniversary in 1976.

Organizers of celebrations months in the making had to adjust or cancel activities entirely as much of the East Coast sweltered under heat that approached and in many cases surpassed triple digits. In Philadelphia, fireworks began to crack as early as midday near Independence Hall, where hundreds of visitors were gathering to await celebrations coinciding with the France-Paraguay World Cup knockout game at Philadelphia Stadium.