(KMOV) -- Police are investigating what caused a driver to veer off the road and travel down a 150-foot embankment in Hollywood Heights, Illinois Tuesday morning
According to authorities, the accident happened on IL-159 north of Bethel Mine Road around 1 a.m.
A female driver called police when she saw the Jeep Cherokee veer off the road, miss the guardrail and drive down a large embankment.
Emergency crews removed the male driver from the vehicle and transported him to Barnes Jewish Hospital.
He was conscious and breathing when he arrived, but the extent of his injuries is unknown.
Police think the man fell asleep at the wheel, but continue to investigate.
A tow truck pulled the vehicle from the deep embankment.
No other vehicles were involved.