At least 13 people were injured on Saturday in what the authorities described as a “possible boat explosion” near a sandbar north of Miami Beach.

More than 25 units from Miami-Dade Fire Rescue, along with the Florida Fish and Wildlife Conservation Commission and the U.S. Coast Guard, responded to a call around 12:50 p.m. near the Haulover Sandbar, a shallow sand flat about 10 miles north of Miami Beach.

When emergency responders arrived, they found multiple people with burns and other minor injuries, Batallion Chief Juan Arias of the Miami-Dade Fire Rescue said.

Chief Arias added that other people had “somewhat traumatic injuries.”

Miami-Dade Fire Rescue said that it took 11 people from the scene to hospitals. Initial reports had put the number of injured people at 15.

Jackson Memorial Hospital in Miami was treating 13 people who were injured, according to Carla Palmer, a spokeswoman for Jackson Health System.

Four of those taken to Jackson Memorial Hospital were in critical but stable condition, while seven others were in good condition, Ms. Palmer said. Two pediatric patients were also in good condition, she added.

A charter vessel was carrying passengers in Biscayne Bay near the sandbar when an explosion happened on board, said Melissa Brevik, a spokeswoman for the Florida Fish and Wildlife Conservation Commission.

Some passengers on the vessel were injured and taken to hospitals, she said. A preliminary investigation indicated that only one vessel was involved.

Officials did not offer additional details about what led up to the emergency call.

The Haulover Sandbar in Biscayne Bay is a popular social destination that frequently draws large crowds of boaters on weekends and holidays. The sandbar is known for its shallow, clear water and party-like atmosphere, where visitors swim, kayak, snorkel and sunbathe.