PHILADELPHIA (AP) — Severe thunderstorms across the Northeast on Sunday slowed operations at airports, wreaked havoc at outdoor sporting and musical events in New York and Philadelphia and sent people scurrying from a beach after three men were struck by lightning.

The men were injured at Orchard Beach on Pelham Bay in the Bronx on Sunday evening as bad storms rolled through the area, the Fire Department of New York said. The men were being treated at a hospital, and the extent of their injuries was unknown.

Torrential rain, thunder and lightning interrupted Labour Day weekend celebrations in Philadelphia, where a parkway hosting a music concert was evacuated for safety reasons. Organizers of the Made in America festival warned people to move quickly and calmly to the exits and to protected areas outside the downtown festival site until the bad weather passed.

Anne Beyens, of Scottsdale, Arizona, was among a group of five waterlogged friends who were told to leave the concert after watching deejay 3LAU and ended up at a bar a mile away. They said most of the headliners they wanted to see, including Pharrell Williams and Kings of Leon, were scheduled for later in the night so they were hoping to return.

“We knew it was going to rain,” Beyens said. “We didn’t know they were going to kick us out.”

Besides temporarily stopping the Made in America concert, the bad weather also forced the early end to the Electric Zoo musical festival on an island in New York’s East River and halted play for the first time at this year’s US Open tennis tournament in Queens.

Former champion Maria Sharapova took notice of the screeching weather warnings on reporters’ cellphones as she answered questions about her loss to 10th-seeded Caroline Wozniacki just before the storm hit.

“Is that the flood warning? Darn it. If I was only there a little longer,” she said to laughter.

Electric Zoo spokesman Stefan Friedman said “the safety and security of all attendees, artists and staff” was the primary concern as people were told to leave. The decision was made about six hours before the festival was scheduled to end on Randall’s Island, where fans have to take ferries and shuttle buses.

The National Weather Service said it had reports of wind damage and flash flooding in East Orange, New Jersey, and reports of large tree branches down on Long Island. It said most of the damage was reported between 4:20 pm and 5:15 pm, when the storms were intense.

More than 30 flights in and out of the New York metro area were delayed and at least one was cancelled because of the severe weather, according to the flight tracking website FlightAware. Storms also disrupted air travel in Philadelphia and the Baltimore-Washington region.

Flights leaving Newark Liberty in New Jersey and Washington Dulles in Virginia were held up nearly three hours, the Federal Aviation Administration said. Flights in and out of New York’s Kennedy Airport and Philadelphia International Airport were delayed up to two hours.

In the Midwest, storms began sweeping across Iowa and Nebraska late Sunday with heavy rains causing some flooding and wind gusts affecting power lines and snapping tree limbs.

The National Weather Service said Sergeant Bluff, Iowa, and Dakota City, Nebraska, saw straight-line winds of 80 mph to 90 mph that caused significant damage.

The Omaha World-Herald reported that in the Omaha metro area, at least eight people were rescued Sunday evening on the Elkhorn River.

Cleveland’s game at Kansas City was suspended due to rain with the Indians leading the Royals 4-2 heading into the bottom of the 10th inning. The game will resume on Sept. 22 in Cleveland.