U.S. safety officials opened a preliminary investigation into Tesla's Autopilot after identifying 11 crashes involving the driver assistance system, officials said Monday.

The incidents dating back to 2018 included one fatal crash and seven that resulted in injuries to 17 people, according to the National Highway Traffic Safety Administration (NHTSA).

The agency "is committed to ensuring the highest standards of safety on the nation's roadways," a spokesperson said, and in order to "better understand the causes of certain Tesla crashes, NHTSA is opening a preliminary evaluation into Tesla Autopilot systems."

Tesla founder Elon Musk has defended the Autopilot system and the electric automaker warns that it requires "active driver supervision" behind the wheel.

But critics, including in Congress, say the system can be easily fooled and that the system's name gives drivers a false sense of confidence. They have called for NHTSA to take action.

The crashes cited by NHTSA involved incidents in which "various Tesla models crashed" in instances where first responders were involved, including "some that crashed directly into the vehicles of first responders," the NHTSA spokesperson said.

Three of the crashes took place in California, while others happened in Florida, Texas and Massachusetts, and other states. The probe covers models Y, X, S and 3, the agency said.

"NHTSA reminds the public that no commercially available motor vehicles today are capable of driving themselves," the spokesperson said.

"Certain advanced driving assistance features can promote safety by helping drivers avoid crashes and mitigate the severity of crashes that occur, but as with all technologies and equipment on motor vehicles, drivers must use them correctly and responsibly."

News of the probe sent Tesla shares sharply lower Monday.

Investigations such as the one announced Monday sometimes lead to recalls. In June, Tesla recalled more than 285,000 cars in China due to problems with the cruise control system that authorities there said could lead to collisions.

However, analysts said such a recall could involve a software update rather than a more hardware change that requires costly equipment upgrades.