Washington - The chairman of the Arkansas state Democratic Party, Bill Gwatney, 48, was shot dead Wednesday at the party headquarters in Little Rock, police said.

A gunman walked into the office, asked to speak to Gwatney and fired several shots, fatally wounding him. He died four hours later in hospital.

The shooter fled in a pickup truck, was chased by police and killed in an exchange of gunfire on a highway, the Arkansas Democrat- Gazette reported.

Police later identified the gunman as Timothy Dale Johnson, 50. They recovered additional weapons from his truck.

Gwatney, whose family owns an auto dealership in the state, was to attend the Democratic presidential convention later this month.

Democratic presidential candidate Barack Obama released a statement saying he was "heartbroken to hear about the tragic loss of Chairman Bill Gwatney. We're praying for his family and friends and all who worked with him and loved him."