Boston fire officials have determined that lithium-ion batteries caused the three-alarm fire in Dorchester that claimed the life of veteran Boston firefighter Robert “Bobby” Kilduff Jr. in May.

According to the Boston Globe, investigators found that multiple lithium-ion batteries stored inside plastic toolboxes sparked the fire at 18 Treadway Road on May 23rd.

Kilduff, a 24-year veteran of the Boston Fire Department and member of Rescue Company 2, died after falling from the third floor while battling the blaze. He was a third-generation firefighter, Marine veteran, and father of two.

During a press conference Wednesday, Fire Commissioner Rodney Marshall said the batteries experienced a process called “thermal runaway,” which occurs when battery cells overheat and trigger a chain reaction.

Officials are reminding residents to properly charge and store lithium-ion batteries, which are commonly found in cell phones, power tools, electric bikes, and scooters.

While the cause of the fire has been determined, investigations into the circumstances surrounding Kilduff’s death remain ongoing.

Councilor Flynn Calls for Hearing on Lithium-Ion Battery Safety

In related news, Boston City Councilor Ed Flynn has filed a hearing order to address public safety concerns surrounding lithium-ion batteries used in electric bikes, scooters, and other micromobility devices.

Flynn is calling for a closer look at battery storage, fire prevention, and potential regulations as incidents involving lithium-ion batteries continue to raise safety concerns across Boston.

Other cities, including New York and San Francisco, have introduced restrictions and safety standards for these batteries.

“Residents and property owners deserve decisive action to prevent fires, protect property, and keep our communities safe,” Flynn said in a statement.

The hearing would provide an opportunity to discuss ways Boston can better protect residents and first responders from lithium-ion battery fires.

A hearing date has not yet been announced.