​Investigators: Tesla car was speeding at time of crash

Last Updated Jul 26, 2016 4:37 PM EDT

WASHINGTON - Federal investigators say the driver who was killed when his Tesla (TSLA) sedan crashed while in self-driving mode was speeding just before hitting the side of a tractor-trailer.

The National Transportation Safety Board said in a preliminary report Tuesday that the Tesla Model S was traveling at 74 mph in a 65-mph zone on a divided highway in Williston, Florida, near Gainesville.

The report says the driver, Joshua Brown, 40, a tech company owner from Canton, Ohio, was using the sedan's cruise control and lane-keeping features at the time. Those features are part of the vehicle's Autopilot self-driving system, but the NTSB report doesn't mention the system.

The National Highway Traffic Safety Administration, which also is investigating the crash, has said the Autopilot was engaged.

The Tesla's roof struck the underside of the truck's 53-foot semitrailer at a 90-degree angle, shearing off the sedan's roof before it emerged on the other side of the trailer, according to the report. The truck was making a left turn at the time.

The sedan is equipped with automatic emergency braking. Tesla and NHTSA have previously said the Autopilot was unable to distinguish the white side of the truck from the brightly lit sky and there was no attempt to brake by either the self-driving system or Brown.