Several people were injured after a possible boat explosion near the Haulover Sandbar in Miami, Florida, prompting a large emergency response on Saturday afternoon.

Miami-Dade Fire Rescue transported 11 people to hospitals with burns and other serious injuries, and officials upgraded the incident to a mass casualty response due to the number of victims.

Witnesses reported seeing people thrown from the boat and flames spreading rapidly, though authorities have not confirmed the exact cause of the incident.

The vessel, a 40-foot charter cruiser, was later found docked nearby as investigators with multiple agencies worked to determine what happened, CBS News has reported.

Officials are urging boaters to follow safety precautions while the investigation continues.