Two of those were in serious condition after the blast in the town of Plantation in south Florida.
Photos on US news outlets showed a large field of debris strewn across the parking lot of the Fountains Plaza shopping center, with major damage in particular to an LA Fitness gym.
Between 15 and 20 people were injured, deputy fire chief Joel Gordon said. His department initially called it a gas explosion and Gordon said ruptured gas lines were found in the debris, but that the cause of the blast has not been confirmed.
No one has been reported missing. “As bad it was, it could have been a lot worse,” Gordon said.
A major avenue running past the mall was shut down. Plantation is about 50 kilometers (30 miles) north of Miami.