A lithium-ion battery meant for an electric scooter burst into flames in a Chelsea apartment, injuring five people and prompting a reminder from fire officials on how to safely handle the popular devices.

Chelsea firefighters responded to 32 Carmel St., at about 12:40 a.m. last Saturday after receiving reports of a fire. As they arrived, they observed smoke and flames on the first floor in the rear of the three-story, four-unit dwelling, the state Fire Marshal’s Office said in a release Wednesday.

Firefighters quickly extinguished the fire, but four occupants of the building were taken to the hospital for treatment of injuries that authorities described as not life-threatening.

The Chelsea Fire Department and Massachusetts State Police fire investigators determined a  “lithium-ion battery intended for an electric scooter had been left charging for several hours, caught fire, and exploded,” the state Fire Marshal’s Office said in the release.

“The high energy density of lithium-ion batteries means they pack a lot of power into a small device,” State Fire Marshal Jon M. Davine said. “Overcharging, overheating, and physical damage can cause them to fail rapidly and violently, like this one did. Fortunately, the residents were awake and aware of the danger. A few hours later and this could have been a very different story.”

Firefighters across Massachusetts are facing the “nearly impossible” task of extinguishing lithium-ion battery fires more than ever, according to data the state released last month. The figures showed how such blazes have spiked sharply since last October.

Roughly 38 cities and towns identified 50 lithium-ion battery fires between last October and the middle of April, more than double the annual average detected by a national fire data reporting system.

“The increase since last fall could be due to the growing number of consumer devices powered by these batteries, increased attention by local fire investigators, or other factors,” Davine said last month.

The state Department of Fire Services created a checklist last fall to make it easier for local departments to track the number of fires caused by lithium-ion batteries, which power large devices like electric vehicles and smaller items like smartphones and e-cigarettes.

“Lithium-ion batteries power many of the devices we use every day,” Chelsea Fire Chief John Quatieri said in a release. “It’s important to use, charge, and store them according to the manufacturer’s instructions.”

“Always use the original charging equipment, disconnect it when the device is fully charged, and protect it from damage or abuse,” he added. “If you use an e-bike or electric scooter, store it outside if possible. If you must store it indoors, keep it clear of doors, windows, and other escape routes.”