EL DORADO HILLS, Calif. (AP) — Five children under the age of 15 have been injured on Folsom Lake after a fuel vapor flash on a boat.

Folsom Lake Marina officials say the man operating the 18-foot boat had just put fuel in it before subsequently starting the engine on Sunday, which may have ignited the fuel vapors. Everyone on the boat jumped off and was helped to safety after the explosion.

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“We talked to one of the dock workers and they said there was an engine fire and some girls got burned badly,” a witness said.

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The victims were taken to a hospital to get treatment for first- and second-degree burns.

All five victims are expected to survive.

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Alisa Schaedler, a witness who arrived at Brown’s Ravine Marina just after the incident, says a good vapor flash example is when a barbecue backfires after lighting it with the lid on.