By David Shepardson

WASHINGTON (Reuters) -The National Highway Traffic Safety Administration (NHTSA) said on Friday it will open a special investigation into a Florida crash on Wednesday that killed a 66-year-old Tesla (NASDAQ:TSLA) driver and a 67-year-old passenger.

A 2015 Tesla rear-ended a parked tractor-trailer in the Gainesville area at a rest area off Interstate 75, the Florida Highway Patrol said. Both people in the Tesla, who were from Lompoc, California, were pronounced dead at the scene. A patrol spokesman said it was unclear if Autopilot was in use.

On Thursday, NHTSA confirmed it had opened a special investigation into a fatal pedestrian crash in California involving a 2018 Tesla Model 3 in which an advanced driver assistance system was suspected of having been in use.

NHTSA has previously opened 36 special crash investigations - including the California crash - involving Tesla Inc vehicles in which advanced driver assistance systems like Autopilot were suspected of being used since 2016.

A total of 17 crash deaths have been reported in those Tesla investigations, including the Florida crash.

NHTSA typically opens more than 100 special crash investigations annually into emerging technologies and other potential auto safety issues that have, for instance, previously helped to develop safety rules on air bags.

Tesla, which has disbanded its press office, did not respond to a request for comment.

The Florida crash bears similarities to a series of crashes under investigation by NHTSA.

In June, NHTSA upgraded its defect probe into 830,000 Tesla vehicles with Autopilot, a required step before it could seek a recall.

NHTSA opened a preliminary evaluation to assess the performance of the system in 765,000 vehicles after about a dozen crashes in which Tesla vehicles struck stopped emergency vehicles - and said last month it had identified six additional crashes.

NHTSA Administrator Steven Cliff told Reuters on Wednesday he wants to complete the Tesla Autopilot investigation "as quickly as we possibly can but I also want to get it right. There's a lot of information that we need to comb through."