The top vehicle safety regulator in the U.S. has launched a formal probe into an April crash involving the all-electric VinFast VF8 SUV that claimed the lives of a family of four, TechCrunch has learned.

The crash happened in Pleasanton, California at about 9 p.m. on April 24. Police told local news outlets at the time that it appeared the vehicle lost control before crashing into an oak tree and catching fire. A spokesperson for the National Highway Traffic Safety Administration (NHTSA) told TechCrunch on Monday that its Special Crash Investigations division will “document the crash circumstances and the ensuing fire.”

The victims, who have been identified by the Alameda County Sheriff’s Department as Tarun and Rincy George, and their two children, did not own the vehicle.

A few days after the crash, a complaint was lodged with NHTSA that explained the owner had loaned the EV to a co-worker. The purported owner had experienced at least one instance where the car’s lane assist feature had jerked the vehicle to the right, according to the complaint.

The National Transportation Safety Board told TechCrunch on Monday that it has not opened an investigation into the crash. The Pleasanton Police Department said its own investigation is ongoing. VinFast did not immediately respond to a request for comment.

Vietnamese EV-maker VinFast started shipping its VF8 SUV to the U.S. in early 2023. The rollout has not gone well. The company was pilloried by reviewers for poor quality. In May 2023, it issued a recall over problems with the dashboard screen going blank. At least one other complaint lodged with NHTSA at the time this article was published references an incident where the driver assistance system unexpectedly turned the wheel.