(NewsNation) — More people are buying electric vehicles as technology improves and gas prices are on the rise. Axios reports that electric vehicle registrations doubled over the past year, making up 5% of new cars.

But some areas are seeing more enthusiasm for these vehicles than others. For instance, the number of electric vehicle sales tends to increase on the West Coast. San Francisco has the most, with more than 20% of the electric vehicles registered in the Bay Area. According to Forbes, the city has a reported 52 charging stations per 100,000 residents.

While the East Coast has also shown interest in electric vehicles, Midwestern states such as Missouri and Oklahoma aren’t as interested, according to Axios.

Even with certain areas seeing more electric vehicles on the road, a shift to gasoline will take years to play out from Axios’ estimation. Right now, Tesla dominates the industry, Axios wrote, and accounted for 61% of all American electric vehicles registered in April. Ford also tops the list, though at a much lower percentage: 8%.

An increase in electric vehicles means a new issue for fire departments across the country. Electric vehicle fires are less common than gas-powered ones but can be much more difficult to put out, requiring 10 times as much water to extinguish. That’s because these vehicles use high-voltage lithium-ion batteries. One Tesla in a Sacramento junkyard’s batteries kept reigniting flames three weeks after it was involved in a crash. It eventually took 4,500 gallons of water to put out the blaze. In comparison, gas-powered vehicles are typically extinguished with less than 1,000 gallons.

“Once they reach this point, it takes copious volumes of water in order to cool and extinguish these types of fires. The challenge for common fire departments is that we simply do not carry that amount of water on our apparatus,” Lt. Tanner Morgan of the Grand Prairie Fire Department in Texas, said. “Right now we’re in the crux, we’re at that critical point where the consumer-driven world we live in is pushing these vehicles out, and the fire department is playing catch up.”

The National Transportation Safety Board issued a lengthy report two years ago about the safety risks to emergency responders from lithium-ion battery fires.

The agency has urged all-electric vehicle manufacturers to educate first responders since battery configurations vary between makes and models.