One person was killed and three others injured — one critically — in a fiery three-car crash on the Seven Mile Bridge that shut down U.S. 1 until 8:30 p.m. Thursday, the Monroe County Sheriff's Office said.

The 4 p.m. wreck involved a Florida Fish and Wildlife Conservation Commission sport utility vehicle that caught fire and an FWC boat it was trailering, which fell off onto the road, reports say.

One of two people in the SUV, believed to be a biologist, died at Fishermen's Hospital, according to sheriff's spokeswoman Becky Herrin.

Another victim — it was unclear at press time if it was the other occupant of the SUV  — was in critical condition at Lower Keys Medical Center, said Florida Highway Patrol spokesman Alex Annunziato.

Another accident victim was airlifted to Ryder Trauma Center in Miami with a broken femur and was in stable condition as of press time, reports say.

The fourth victim was at Fishermen's Hospital, but his or her identity and condition were unknown.

Rescue workers had removed one of the FWC officers from the burning truck. It was unclear at press time whether that was the biologist who died.

Who and what caused the crash remained under investigation Thursday night. A trooper supervisor investigated the wreck and a crash reconstruction team was still on the scene as of 6 p.m., Annunziato said.

The Seven Mile Bridge was reopened at 8:30 p.m., Herrin said.

FHP had not released the names and residency of those injured, the types of vehicles involved, or who was in which vehicle.

Rescue workers doused the flames with foam, and about 40 gallons of gasoline spilled into the Atlantic Ocean, according to the Sheriff's Office.

alinhardt@keysnews.com