FREDERICK, Md. (AP) — A Maryland sheriff's office is trying to determine who organized an illegal street racing event that left a man dead and a teenager injured after the two were thrown from the back of a truck.

Michael Fritz, 22, died on Sunday of injuries sustained in the accident in Frederick, the Frederick County Sheriff’s Office said in a statement Monday.

John Wittington Jr., 19, was hospitalized but improving, officials said.

Deputies were responding to a call that a large group of people were racing vehicles around 10:15 p.m. Friday when they found Fritz and Wittington injured. Deputies determined the two were riding in the bed of a 1984 Ford flatbed pickup when it left the road and the two fell, the sheriff's office said.

The men, as well as a 19-year-old driver who wasn't seriously hurt, had been participating in a "pop-up street race event” that was organized on social media, the office said.

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