Crowds had been gathering at the mall for Wednesday night's Fourth of July festivities -- a concert emceed by Tony Danza with performances by Little Richard, Bebe Neuwirth and the National Symphony Orchestra, capped off by a fireworks display over the Washington Monument at 9:10 p.m. EDT.
CNN said the concert had been postponed, but WCBS-TV later reported that authorities said the activities would continue as planned, and expected crowds would be allowed to return to the mall around 7:30 p.m.
At around 5 p.m., the Park Service closed off checkpoints visitors needed to pass through to gain access to the mall, and advised those who were already there to seek shelter.
CNN said a tornado warning had been posted for nearby Howard County in Maryland, and for Fairfax County, Va.
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