The blast happened near the LA Fitness at the Fountains , 1041 S University Dr. in Plantation. The possible ground zero was a vacant pizza restaurant undergoing renovation, according to authorities on the scene.

"As bad as it is, it could have been a lot worse," according to a Plantation fire official.

He said crews are still searching for victims. The injured have been taken to Broward Health.

A Broward County "technical rescue team" is at the mall and firefighters are searching the rubble with dogs.

LA Fitness customers evacuated the building. Some appeared injured.

All stores at the shopping center have been closed until further notice. Surrounding roads, including University Drive near Peters Road, also have been blockaded by police.

The explosion appears to have originated at a vacant business undergoing remodeling, said witness Michael Lind, a contractor and former firefighter who helped evacuate people from nearby businesses.

Lind said the business was "leveled" and sent sheet metal flying toward parked cars and across the parking lot. He said the force of the blast shattered windows of nearby businesses and caused the gym's roof to collapse.

"The vacant shop being remodeled was the one that exploded," he said. "The only thing that was left was some of the framework. It exploded both ways, it went north south and to the west. It blew the windows out at LA fitness and it collapsed the roof."

Lind said he called 911, telling the operator to " send everything they had."

He said he smelled gas, and that some people were bleeding.

There are no reported fatalities, according to NBC 6, citing Plantation police.

"It was like a war zone," Lind said. "I've seen buildings blow up in the past but I've never seen it like this. it was just so much debris. The sheet metal was twisted. There was a lot of energy behind that explosion."

Lind said it appeared to be a natural gas explosion.

"Maybe they didn't shut the gas off," he said.

Residents several miles away in Davie felt the boom and started hearing sirens immediately.

"All stores and businesses in the area of the Fountains Plaza and the Plantation Marketplace plaza near LA Fitness will be shut down until futher notice until Fire Personnel can determine that it is safe to return," Plantation Police posted on Twitter. "Please do not come into this area if possible."

Christina J, who declined to give her last name, was working at LA Fitness in the Kids Club around 11:30 a.m. when she heard a bang.

"We just felt the whole building shake," she said. "The ceilings started collapsing in. The windows blew in."

She saw two bright lights at the time of the explosion, which immediately sent gym members scrambling in a panic to the exits. Parents rushed to find get their children.

There was no screaming or running, she said, but "everyone was trying to get out."

Outside, water was everywhere, presumably from a burst water line. She said there was dust heavy in the air, but no smoke. Car alarms blared.

She found her husband, William, who had just arrived at the place to pick her up. They were both unhurt, but their car, like many in the immediate parking lot, was damaged, its front windshield blown in.

Allison and Kathy Thibert, who live about two miles away near Mirror Lake Elementary, said the blast shook their whole house.

Thibert's husband, Richard, was outside looking in the opposite direction and saw a flash.

"Everything shook," said Thibert, who went with her daughter, Allison, to the Fountains shopping plaza across the street to see the scene after learning of the site of the explosion.

"At first he thought it was a storm and I said 'this isn't lightning.'"

• Technically, he broke the law, but is Tommy Robinson really in prison because he drew attention to 'grooming gangs'?
• Un-free speech: Tommy Robinson arrested for talking into his phone outside court hearing for Leeds grooming gangs
• 'I don't care if I incite fear of Muslims, as long as it prevents children from being raped' - Tommy Robinson in heated interview
• UK government has turned Tommy Robinson into de facto "persona non grata"
• UK MPs want Tommy Robinson banned from social media
• PayPal bans Tommy Robinson for 'promoting hate & violence'
• Tommy Robinson banned from Facebook and Instagram
• YouTube clamps down on Tommy Robinson's channel with series of restrictions
• Election meddling: Sargon of Akkad and Tommy Robinson's campaign Twitter accounts deleted before EU Parliament vote

• Texas State University Students demand censorship of conservative group in the name of 'Free Speech'
• Anarchist university group threatens to dox students who join conservative clubs

• Horrifying New York late-term abortion law at forefront of big Democrat push in US
• Suicide pod makes its debut at Amsterdam funeral show
• Dutch teen raped as a child chose to be legally euthanized due to 'unbearable' pain - Update: Teen was not actually euthanized
• Insane! UK court orders disabled woman to have an abortion despite her and her family's objections

• The Health & Wellness Show: Suicide and Euthanasia: A valid choice or the easy way out?
• Objective: Health - Law or Flaw? Let's Talk About Abortion