Tesla has come under fire in the wake of an explosive crash in Indianapolis involving a Model S battery-electric vehicle that took the life of a young woman and her boss.

The automaker had previously taken steps to prevent the lithium-ion batteries used in its vehicles from inadvertently catching fire, but the crash raises questions not only about whether Tesla has gone far enough, but whether Tesla’s battery technology is inherently safe. Lithium-ion chemistry came under close scrutiny last year as a result of fires and meltdowns involving Samsung’s Galaxy Note 7 smartphone.

“Had she been in another vehicle she would have been alive for me to yell at her for driving after drinking,” Jon Speckman, the father of victim Casey Speckman, said during an interview with the Indianapolis Star.

Explosion Upon Impact

The 27-year-old was driving her boss’s Model S battery-electric vehicle about 1 a.m. on November 3, when they appear to have swerved to avoid a car driving in the wrong direction, crashing into a tree and then a parking garage in Indianapolis. The car almost immediately exploded. Speckman, who was found to have a blood-alcohol level of 0.21 percent — nearly triple Indiana’s 0.08 percent limit — was killed by the crash, but 44 year-old Kevin McCarthy died as a result of the subsequent explosion and fire.

Emergency responders reported that when they arrive at the scene, individual batteries from the Tesla’s pack were popping out of the vehicle and exploding.

Analyst Dave Sullivan, himself an electric vehicle owner, said he wasn’t entirely surprised by what happened. “Like a gasoline vehicle, an EV’s energy source can be explosive when it gets into a serious enough accident,” said Sullivan, an analyst with AutoPacific. “I don’t know if there’s an answer to the explosive nature of lithium-ion when those batteries are disturbed.”

Other Incidents

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This is not the first time Tesla has come under scrutiny as a result of fires involving its vehicles. The maker’s Model S was involved in several other well-publicized incidents in 2013, most of the fires triggered by road debris unexpectedly puncturing the battery pack. Tesla quickly responded by adding a new titanium shell that reduced the likelihood of such punctures.

Related: Electric Car Blaze Raises Questions for Tesla

Separately, CEO Elon Musk downplayed the risk, noting that there are “thousands” of gasoline-powered vehicles that are involved in fires every year. Referring to one of the Tesla incidents on a Washington State highway, he said in a blog post, "Had a conventional gasoline car encountered the same object on the highway, the result could have been far worse.”

Tesla told NBC News, “We have been deeply saddened by this accident and have been working closely with authorities to facilitate their report. While it can be difficult to determine the precise speed of a vehicle in such a crash, the observed damage and debris field indicate a very high speed collision.”

In a 2013 blog post, CEO Musk also declared that, "For consumers concerned about fire risk, there should be absolutely zero doubt that it is safer to power a car with a battery than a large tank of highly flammable liquid."

Despite the comments made by Casey Speckman’s father, it is difficult to say if any gasoline-powered vehicle would have behaved better in the Indianapolis crash, according to several auto industry insiders who were reluctant to discuss the incident on the record. While cars don’t routinely explode like they do on TV and in movies, there are, indeed, many fires that result from high-speed crashes. And witnesses to the Indianapolis crash told authorities the Model S was going well above the speed limit.

Shortly after the investigation into the fatal crash, Indianapolis Fire Department Battalion Chief Kevin Jones told a press conference, "If you have collisions at high rates of speed with impacts like that, regardless if it’s a traditional power vehicle via gasoline or hybrid or all electric, you can see a fire in a vehicle like that or severe damage. And so to say it was simply because it was an electric vehicle, you can’t say that because we’ve seen collisions that are non-electric vehicles with just as bad of damage or fire.”

Lithium Problems

The incident, nonetheless, highlights concerns about lithium technology at a time when the chemistry is again coming under close scrutiny. There have been enough reports of fires and meltdowns involving the Samsung Galaxy Note 7 that the FAA barred passengers from carrying the smartphone onto commercial airplanes. A number of airlines have now severely restricted — or barred entirely — shipment of lithium batteries in cargo holds.

Experts note that there are actually more than a dozen different “families” of lithium-ion chemistry. Each has different characteristics — such as the amount of energy they can store and how quickly they can be charged. Unfortunately, some of the most “energy dense” versions are also more prone to catch fire due to both manufacturing failures and accidents that could short the batteries out. Automakers like Tesla have shied away from those formulations, accepting slightly poorer performance in return for lower risk.

Nonetheless, lithium chemistry isn’t entirely risk-free. But both the National Highway Traffic Safety Administration and the industry-funded Insurance Institute for Highway Safety have so far accepted what the industry has done to mitigate such problems.

Other Electric Cars Have Had Fires

Tesla, incidentally, isn’t the only automaker to experience a battery fire. General Motors was involved in a couple of incidents shortly after introducing its first-generation Chevrolet Volt plug-in hybrid. But a fire that was triggered by a NHTSA test was later ruled to be the result of the government’s improper test procedures, not a battery defect.

Meanwhile, Tesla took heat for a different safety issue last year, following several crashes potentially linked to its semi-autonomous Autopilot technology. The automaker has acknowledged only one crash was linked to the system, and federal safety regulators subsequently determined that the primary problem was the driver’s failure to take steps to stop the vehicle before it crashed into a semi-truck. Scott Brown, a former Navy SEAL, was killed in the May 2016 incident. Tesla has since updated its Autopilot technology.