An owner of a 2015 Tesla Motors Model S was killed in Florida in May while the car was in Autopilot self-driving mode, the automaker confirmed Thursday. The National Highway Traffic Safety Administration (NHTSA) is opening an investigation into the crash.

The accident raises concerns about the future of autonomous technology while it is still in its developmental “beta” stage—and the risks of experimenting with it on public roads. Tesla, Mercedes-Benz, and other luxury brands have recently debuted self-driving features, with differing degrees of autonomous driving.

Tesla says that its self-driving software “is new technology and still in a public beta phase,” and that its large central screen requires drivers to acknowledge the fact before they activate Autopilot in their cars. The system allows drivers to relinquish control to the Tesla’s computer for the vehicle’s speed, intelligent cruise control, some measure of steering, and even changing lanes.

Jake Fisher, Consumer Reports director of auto testing, says consumers should be wary of operating vehicles with self-driving features while the technology is still in its nascent stage. Consumer Reports testing of Tesla's Autopilot feature has shown that while the technology is impressive, it doesn't make the car truly self-driving.

“Naming the system Autopilot is a bit misleading,” Fisher says. “This is a suite of technology still in its beta stages and is not yet capable of complete autonomous driving. This accident calls into question the wisdom of rolling out unproven technology to the public.”

The accident, which happened May 7 near Williston, Fla., occurred when 40-year-old Joshua Brown of Ohio was behind the wheel of his Tesla when it drove under the cargo trailer of an oncoming big-rig truck, which turned left in front of him.

According to a report of the crash, published in the Police Beat section of the Florida Levy Journal, the roof of Brown’s car struck the underside of the trailer as it passed under the trailer.

“The top of Joshua Brown’s 2015 Tesla Model S vehicle was torn off by the force of the collision,” the Levy Journal report states. “The car continued to travel east on U.S. 27A until it left the roadway on the south shoulder and struck a fence. The car smashed through two fences and struck a power pole. The car rotated counter-clockwise while sliding to its final resting place about 100 feet south of the highway. Brown died at the scene.”

In opening its preliminary investigation, NHTSA says in a release: “NHTSA’s Office of Defects Investigation will examine the design and performance of the automated driving systems in use at the time of the crash. During the preliminary evaluation, NHTSA will gather additional data regarding this incident and other information regarding the automated driving systems.

“The opening of the preliminary evaluation should not be construed as a finding that the Office of Defects Investigation believes there is either a presence or absence of a defect in the subject vehicles,” the agency states.

Consumer Reports believes that it's not enough for automakers to self-certify that their beta technology is safe.

“Autonomous vehicles fundamentally change the relationship between consumers and their cars,” says William Wallace, an analyst for the policy and mobilization arm of Consumer Reports.

“Federal standards should include expert and independent third-party testing to ensure these cars detect and react appropriately to hazards on the road. Self-driving cars must be rigorously tested—under a variety of environmental conditions—to prevent tragedies like this in the future,” Wallace adds.

According to a blog on the Tesla Motors site, “Neither Autopilot nor the driver noticed the white side of the tractor trailer against a brightly lit sky, so the brake was not applied. The high ride height of the trailer combined with its positioning across the road and the extremely rare circumstances of the impact caused the Model S to pass under the trailer, with the bottom of the trailer impacting the windshield of the Model S.”

Tesla describes Brown as “a friend to Tesla and the broader EV community, a person who spent his life focused on innovation and the promise of technology and who believed strongly in Tesla’s mission.”

(Our sister website Consumerist has more details about the depth of Brown’s interest in autonomous car technology.)

A Tesla spokeswoman tells Consumer Reports: “Today’s Autopilot features are designed to provide a hands-on experience to give drivers more confidence behind the wheel, increase their safety on the road, and make highway driving more enjoyable. Autopilot is by far the most advanced such system on the road, but it does not turn a Tesla into an autonomous vehicle and does not allow the driver to abdicate responsibility.

“If the Autopilot system loses any level of confidence in its ability to safely operate, the driver will be alerted with a visual and auditory warning, asking the driver to place their hands on the wheel, or take over immediately depending on the severity of the road conditions,” the spokeswoman adds.

Tesla says the collective Tesla fleet has now driven more than 2 billion miles, 130 million miles of which have been driven with Autopilot activated.

Correction: This article previously stated that Joshua Brown was 45 years old. He was 40.