Police say the explosion that critically injured the head of an Arkansas medical board was caused by a bomb planted in his car.
Trent Pierce was injured when the device blew up as he left his home in West Memphis today for work.
Pierce is the chairman of a state board that licenses and disciplines doctors.
Police say they believe Pierce was outside the car when the explosion took place. He's hospitalized in Memphis, in critical condition.
An FBI official in Washington says a second person also was injured.
A lawyer for the medical board says he doesn't know of any heated disputes involving Pierce.