An all-terrain vehicle driver was in critical condition and two passengers seriously injured after crashing through a bridge railing, the Forsyth County Sheriff’s Office said Monday.

Investigators believe Matthew Holbrook, 39, was driving the ATV at a high rate of speed late Saturday when he attempted to cross a bridge on Big Creek Greenway, near Cumming, Deputy Epifanio Rodriguez said.

“Holbrook failed to negotiate the curve and drove straight into the wooden railing,” Rodriguez said in an emailed statement. “The ATV went through a section of railing, throwing all three passengers off the ATV and down onto the ground.”

Holbrook and two other men, whose names were not released, were taken to a local hospital for treatment. Holbrook remained in critical condition Monday, Rodriguez said.

No information was available on the type of ATV the three were riding on, but the vehicle is not legal for public roadways.

Speed and alcohol are believed to be contributing factors in the crash, Rodriguez said.