An Alabama prison inmate was killed and three others injured Thursday when a motorist struck them as they worked a cleanup detail beside a highway, state troopers said.

The inmates were picking up debris along Interstate 65 near the Montgomery city limit about 11:15 a.m. when the driver of a small car slammed into a concrete barrier, spun out of control and struck the group, trooper Lt. Chris Williams said.

Department of Corrections spokesman Brian Corbett said Jeffery Allan Holt, 40, serving seven years for felony DUI from Limestone County, was killed.

Nigel Hamilton, 37, serving 20 years on drug charge from Walker County, and Eddie Aaron, 54, serving a 15-year drug sentence from Bibb County, remained in a Montgomery hospital Thursday afternoon, Corbett said.

Inmate Ron Woolen, 30, serving 20 years for burglary and theft from Madison County, was treated and released at the emergency room and returned to Staton Correctional Facility, Corbett said.

Four people in the vehicle also were hurt and taken to a hospital, Williams said. The nature of their injuries was not immediately available.

Holt was the second Alabama inmate in the last two weeks to be struck and killed while working road detail.