A crew had just refueled their boat — then came a big blast, Florida firefighters say

A boat explosion rocked Halifax Harbor Marina in Daytona Beach on Sunday afternoon.

Security video posted on the fire department’s Facebook page shows the frightening incident just as it occurred.

The 15-second video starts out serenely: A white motorboat with the blue sky behind it and grassy patches and a banner swaying in the breeze in front. Three people are on board: One in the front, two in the middle.

Suddenly, boom!

The back portion of the boat explodes, pieces go flying and a fire immediately breaks out. One man who was standing on the dock right by the blast takes off running.

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The next pictures show the Florida firefighters hosing down the damaged vessel, with thick, gray smoke billowing out of the stern. The last picture shows the charred boat sinking.

The fire department says a crew arrived around 1:15 p.m.. Four boaters had just refueled the 34-foot vessel, which blew up when they tried to start its engine.

No cause for the explosion was released. The Daytona Beach Fire Department didn’t return a call Monday asking for more details.

All four people seen in the video were injured, the fire department says, and one was airlifted to an Orlando hospital for burns.