Under pressure from U.S. safety regulators, Ford is recalling about 2 million F-150 pickup trucks in North America because the seat belts can spark and cause fires.

The recall, which covers trucks from the 2015 through 2018 model years, comes about one month after the National Highway Traffic Safety Administration began investigating fires in the pickups, which are the top-selling vehicles in the United States.

Ford said Thursday that it has 23 reports of smoke or fire in U.S. and Canadian trucks, but it’s not aware of any injuries. NHTSA began investigating in early August after getting five fire reports, including three reports that trucks were destroyed.

According to Ford, seat belt pretensioners can generate excessive sparks when they tighten before a crash. That can ignite gases inside a support pillar between the front and rear seats, causing insulation and carpet to catch fire.

The seat belt pretensioners, which prepare seat belts to gradually restrain passengers, were made by ZF-TRW and now-defunct air bag and seat belt maker Takata, which was purchased by Joyson, another auto parts supplier.

The Regular Cab and SuperCrew Cab trucks were built between March 12, 2014 and Aug. 23, 2018, according to documents posted Thursday by NHTSA.

Dealers will remove insulation and install heat-resistant tape to repair the trucks. They also will remove remnants of wiring tape and modify interior panels in Regular Cab trucks. Owners will be notified starting September 24.