Preliminary findings released by the National Transportation Safety Board on May 16 indicate that the autonomous vehicle control system onboard a Tesla Model 3 electric car was engaged when the sedan collided with a tractor-trailer near Delray Beach, Florida, around 6:15 a.m. on the morning of March 1.

According to the NTSB report, the Tesla struck the left side of the semitrailer. The roof of the Tesla was sheared off as the vehicle went underneath the trailer and continued south. The Tesla came to a rest on the median, about 1,600 feet from where it struck the trailer. The 50-year-old male Tesla driver died as a result of the crash. The 45-year-old male driver of the tractor-trailer was uninjured.

In reconstructing the accident, NTSB said it determined that as the Tesla approached a private driveway, the tractor-trailer pulled out and traveled east across the southbound lanes of U.S. Highway 441. The truck driver was trying to cross the highway’s southbound lanes and turn left into the northbound lanes. According to surveillance video in the area and forward-facing video from the Tesla, the combination vehicle slowed as it crossed the southbound lanes, blocking the Tesla’s path.

Additionally, NTSB said, preliminary data from the vehicle show that the Tesla’s Autopilot system— an advanced driver assistance system (ADAS) that provides both longitudinal and lateral control over vehicle motion— was active at the time of the crash. NTSB said the driver engaged the Autopilot about 10 seconds before the collision.

From less than eight seconds before the crash to the time of impact, the vehicle did not detect the driver’s hands on the steering wheel, according to NTSB. Preliminary vehicle data show that the Tesla was traveling about 68 mph when it struck the semitrailer. Neither the preliminary data nor the videos indicate that the driver or the ADAS executed evasive maneuvers.

NTSB is continuing to gather information about the crash and plans to examine the driver of the combination vehicle, the motor carrier, highway factors, and survival factors as next steps in the investigative process.

All aspects of the crash remain under investigation as NTSB works to determine the probable cause, with the intent of issuing safety recommendations to prevent similar crashes.