Californian politicians escaped unhurt after a lorry crashed into their assembly building and burst into flames.
The lorry's driver died at the scene, but no one else was believed to have been injured.
Police are treating the incident as a suicide attack, it is reported.
Members at the Capitol in Sacramento were leaving after an evening session.
There were scorch marks on the Capitol in Sacramento, but it did not appear the fire had spread to the marble building.
The truck driver sounded the horn as the vehicle crashed into the Capitol's south doors, an assembly worker says.
The lorry, which was hauling two trailers, belonged to Dick Simon Trucking of West Valley City, Utah.
Mike Houskeeper, a claims examiner with the company, says he does not immediately know who was driving or what was in the truck.