The boys, 18, died while trapped inside the burning vehicle, according to witnesses. One onlooker said he saw the victims moving, struggling to escape from the flames, but no one could help them break free.
A backseat passenger, identified as 18-year-old Alexander Berry of Fort Lauderdale, was thrown from the car and taken to a hospital with undisclosed injuries, according to ABC Miami affiliate WPLG-TV.
Speed may have been a factor in the crash, the NTSB said Wednesday. Its investigation will primarily focus on the emergency response in relation to the electric vehicle battery fire, the agency said, adding that it had plans to have a team of four investigators in South Florida by Wednesday night.
“The goal of these investigations is to understand the impact of these emerging transportation technologies when they are part of a transportation accident,” NTSB Chairman Robert Sumwalt said in a statement Wednesday.
Tesla released a statement Wednesday, saying, it was “working to establish the facts of the incident” and offered its “full cooperation” to local authorities. The car’s autopilot feature was not engaged at the time, Telsa said.
"These two members of our senior class should be finishing their [advanced placement] exams, celebrating things like prom and their upcoming graduation," Pine Crest president Dana Markham said in a statement Wednesday. "Instead, we are mourning their passing. There really are no words to express how deeply this has affected our entire community."
Larry Groshart, who said he witnessed the crash, told WPLG the car appeared to traveling between 50 and 60 mph.
"I saw the car coming too fast quietly, but I could hear the tire roar,” Groshart said. [It] bounced off the first wall, sideswiped it, then hit that corner and immediately burst into flames and moved that way, burning all the way, and it never stopped burning until it was burned up."
ABC News' Matthew Foster contributed to this report.