DETROIT - General Motors is recalling over 640,000 pickup trucks worldwide because hot gas from a high-tech seat belt can set the carpeting on fire.

The recall covers certain 2019 and 2020 Chevrolet Silverado and GMC Sierra 1500 trucks. Also included are some 2020 Silverado and Sierra 2500 and 3500 heavy-duty pickups. All have carpet as a floor covering, and most are in North America.

GM says it uses a small explosion to move a piston that tightens the belts before a crash. The explosion can release hot gas through an opening in a bracket, possibly setting the carpet on fire. The company reports two fires but no injuries.

Dealers will close the opening at no cost to owners. No date was given for the recall to start.