Police and company representatives say more than a dozen other people were wounded.
A security officer for the Virginia-based company Contrack, which builds facilities for military bases, says a suicide attacker drove a vehicle packed with explosives to the exterior wall of the compound and detonated the bomb.
Afghan police say they can't confirm if it was a suicide attack.
The Taliban are claiming responsibility for the attack, saying a suicide car bomber targeted the compound because it was a company working with the Afghan government.
(Copyright 2012 by The Associated Press. All Rights Reserved.)