U.S. safety regulators and Toyota Motor Corp. are investigating the report of the runaway Toyota Prius that accelerated to more than 90 mph on a San Diego, California, freeway before the driver and a California Highway Patrol officer worked together to stop the vehicle without injury. U.S. Transportation Secretary Ray LaHood said two investigators from the National Highway Traffic Safety Administration were sent to join a team from the CHP.

Toyota said its nspectors are also trying to determine what caused the 2008 Prius to surge uncontrollably as it was being driven by owner James Sikes, age 61.

The high-speed incident, which involved a dramatic pursuit by a highway patrol car, has raised new questions about the automaker’s damaging string of recent recalls and whether Toyota has done enough to address consumer complaints about unintended acceleration that have damaged its reputation and sales.

The Prius was taken to a Toyota dealership in El Cajon, California, where Toyota investigators were examining the car, Toyota spokeswoman Celeste Migliore said.

A CHP spokesman in San Diego said the cause of the runaway car incident remains under investigation. “We do not have any initial findings at this point,” she said.

A Toyota spokesman said the carmaker believe the steps it had taken should address the problems with reported unintended acceleration if repairs were completed properly.