This story was reported by Travis Andersen and Martin Finucane of the Globe staff and Globe correspondents Zachary T. Sampson, Claire McNeill, Faiz Siddiqui, Jennifer Smith, Oliver Ortega, and Rachel Riley. It was written by Andersen.
Thousands of revelers packed the Charles River Esplanade Thursday night for the 41st annual Boston Pops Fireworks Spectacular, dancing to live music and cheering for a nighttime display in the skies that came off just before heavy rains and lightning forced an evacuation of the festivities.
Spectators came from around the country, many wearing patriotic shirts, hats, facepaint, and other eye-catching accessories. They were treated to a spectacular 20-minute fireworks display that began shortly after 10 p.m. and lit up the night sky.
But the festivities ended early, and abruptly.
At about 10:30 p.m., a public address announcer informed the crowd that State Police had ordered an evacuation of the area. Heavy rain began falling soon after, interspersed with lightning flashes, forcing spectators to flee, some walking and some running.
David Procopio, a State Police spokesman, wrote in an e-mail that organizers "shot fireworks off early at 10:01 and cut them on short notice because of the severe weather."
"We then ordered the evacuation and cleared the Oval and Lagoon areas out," he said. "Evacuation was relatively orderly."
The downpour forced the Pops to skip its live performance of Tchaikovsky's "1812 Overture," a cherished segment of the annual July 4 celebration, disappointing some revelers.
"They took away the best part of the whole concert," said Pam Capeless, 62, of Randolph.
City officials said the Boston Common Garage was available for people who needed to wait out the worst of the storm.
Saresh Alambath, 36, of Wilmington left the fireworks and huddled with family members on a porch on Revere Street to escape the soaking rains.
"Suddenly, it started pouring," Alambath said.
Scott Ebner, 40, of the South End got caught in the rain at the edge of the Esplanade.
"Little cold, but the world won't end," he said.
Procopio, the State Police spokesman, said organizers moved up the fireworks "once we knew that a strong storm cell was moving toward eastern Mass."
He added, "Once it was clear that a strong storm cell was going to impact Boston, we ordered the concert be shortened (no "1812 Overture," among other cuts) and began evacuating the Esplanade."
He said late Thursday night that authorities were not aware of any storm-related injuries.
The threat of severe weather had prompted officials to move the traditional July Fourth festivities up one day, marking the first time since 1992 that the extravaganza was rescheduled. Spectators began filling the Hatch Shell area at about 4:30 p.m., and the rain held off until just after the evacuation order was given.
Jubilant concertgoers danced throughout the evening to live performances from the Pops, the Beach Boys, and others. The fireworks display followed and got rave reviews.
"Very beautiful," said Louis Yu, a Boston University medical student.
Revelers also enjoyed the music.
Steve Przecioski, 63, of Phoenix, danced with his wife and daughter as the Beach Boys played "Fun Fun Fun," one of their many hits.
"They still have it," said Przecioski. "They really do."
When the festivities began in the late afternoon, organizers made sure that the crowd was festooned in patriotic garb.
Phil Touchette of B4 Productions, the company putting on the event, passed out miniature American flags and said staff members were distributing some 25,000 flags and foam Statue of Liberty crowns.
"We're just trying to make it a patriotic event here," he said. "That's what it's all about."
Claire Richards, 86, of Randolph, sat in a wheelchair earlier in the evening on the outskirts of the concert area and wore patriotic beads around her neck. She said she was attending the celebration for the first time in many years.
"We might as well enjoy it, because you never know what tomorrow brings," Richards said. "There's nothing like being here in person. It's a happy occasion, a beautiful day."
Concertgoers spread tarps and blankets, set down beach chairs, and kicked off their shoes as they carved out territory for the event.
"We came out specifically for this," said Bruce Masatsugu, 61, of San Francisco, who waited for hours Thursday with his family to get a spot near the stage. "And we figured we might as well go do it — do it right."
Boston Emergency Medical Services said 80 people had visited its medical station on the Esplanade, requesting Tylenol, bandages, and ice packs. Ten people were taken to area hospitals, said spokeswoman McKenzie Ridings.
The buildup to the show began just after 7 p.m., with a series of blasts from a trio of small cannons positioned on the banks of the Charles River, drawing applause from the spectators. Governor Deval Patrick shot off one of the blasts and pumped his arms in the air.
Meanwhile, security at the Esplanade was tight, with several hundred state troopers, park rangers, and National Guard personnel patrolling the area. Troopers were both uniformed and in plainclothes, State Police spokesman David Procopio said.
Security measures included bag checks, limits on the sizes of coolers and tents, and a ban on glass containers and alcoholic beverages, he said.
In addition, Procopio said, State and Environmental Police were conducting marine patrols on the Charles, and a State Police Air Wing helicopter provided support from the air.
Bomb squads and hazardous materials teams were on standby.
By late Thursday night, State Police had not reported any arrests.
State Police did not have an estimate on the crowd late Thursday night, which was in the tens of thousands.
Traffic on the Southeast Expressway was standard for the evening rush hour, said Procopio, with the most significant backups on Interstate 93 southbound due to vehicles being rerouted around Storrow Drive, which was closed.
But on the Esplanade, the focus before the rain remained on the entertainment offerings and the camaraderie among strangers who gathered to mark the nation's independence in an event that some people said is unrivaled by similar celebrations in other cities.
"I drive past D.C., I drive past Philadelphia, I drive past New York," said T.C. Jones, 60, a Richmond, Va., resident who travels to Boston every year to celebrate the holiday. "This is the Fourth of July."
Jones wore a red, white, and blue tie-dyed Red Sox shirt and recalled being stationed as an Army paratrooper at Fort Bragg in North Carolina when he first saw the legendary Arthur Fiedler conducting the Pops on television. He decided then that he would eventually make it to Boston.
And even after the rain soaked the crowd, some who attended still had a favorable assessment of the evening, including Adamarie Brini, 49, of Wakefield, who deemed the event "one to tell the grandkids about."
"It ended on a bang, that's for sure, people huddling in doorways," Brini said.
"We got wet. No harm, no foul. We got to see the fireworks."
Travis Andersen can be reached at travis.andersen@
globe.com. Follow him on Twitter @TAGlobe.