Electric scooters powered by lithium-ion batteries likely sparked a recent four-alarm blaze in Medford, according to fire officials who urged people to safely use, store, and charge these devices.

The fire at 43 Allston St. started in a first-floor laundry room, where two badly-damaged, battery-powered scooters were located.

Fire investigators determined that the fire rapidly spread from that point, causing major damage to the two-family home and displacing all four residents. One person was transported from the scene for medical care. A nearby home sustained exterior heat damage.

Firefighters battled the flames from all sides of the structure for about two and a half hours before bringing it under control.

“Lithium-ion batteries contain a tremendous amount of power in a small package,” said Medford Fire Chief John Freedman.

“When they burn, they burn extremely hot, release toxic gases, and can re-ignite even after the fire has been extinguished,” Freedman added. “It’s vitally important to use, store, and charge them safely according to the manufacturer’s instructions.”

Fire officials also recommended the following safety guidelines: