Donahue said in a tweet that there is no gunman.
Mayor Muriel Bowser said in a tweet that DC Fire is treating minor injuries. She didn’t specify how many people were injured.
“You just heard people scream and they just started booking it,” Tom Roussey said. He said with each pop more people panicked. “They’re knocking over barricades …It was just chaos for a few moments.”
The Capital Pride Alliance, which organized the event, said on its website that it expected more than 200 organizations to take part in the 1.5-mile parade. The parade featured floats and vehicles, organizers said.
After the chaos, Capital Pride tweeted that the parade was over but a block party would go on as scheduled.
The incident happened near Dupont Circle.
CNN is reaching out to police for comment.
Developing story — More to come