The National Transportation Safety Board announced Wednesday that it is investigating a crash involving a Tesla that killed two teens and injured a third in Florida.

A gray 2014 Model S reportedly ran off the road Tuesday and struck a concrete wall before catching on fire and killing the two teens inside and injuring a third who was ejected from the car in Ft. Lauderdale.

The driver, who was killed, was identified as Barrett Riley. Edgar Monserratt was also killed. A spokeswoman from Tesla didn't immediately comment on this story.

Police said speed may have been a factor in the crash. Police told CNBC they are not focusing on AutoPilot as a cause, but they reportedly told NBC Miami that they are investigating the battery pack to see why the car caught fire so quickly.

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The NTSB is also investigating a crash involving a Tesla Model X in California in March when a driver was killed, reportedly while using the car's Autopilot system.

Last Friday, the NTSB announced that it had removed Tesla from that investigation after the company made public comments regarding the crash and seemingly blamed the driver.

Before Autopilot was available, Teslas were involved in two high profile fires in 2013, in which drivers ran over metal objects in the road which popped up and punctured the cars' battery packs. The company issued a recall in those cases to install barriers under the car to better protect the batteries.

In two other well-publicized cases, Teslas caught fire after being involved in high-speed crashes.

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Teslas use an array of cylindrical lithium-cobalt aluminum batteries mounted low across the width of the car's floor, as most electric-car batteries are.

Such lithiuim-ion batteries in almost all of today's electric cars use a liquid electrolyte, which is highly flammable. Automakers work to reduce the fire risk by building protective barriers around the batteries, by isolating the cells from one another, and in most cases by using cooling systems to maintain battery temperatures. There's only so much they can do in the case of a high-speed crash, though.

It's important to note that Teslas pass all federal safety standards and meet all crash test criteria for cars for sale in the U.S. as well as other markets.

Scientists in North America and Japan are working on solid state lithium batteries that would not be flammable. Most of those batteries are years away from commercialization, however.