Lithium-ion batteries caused fire that led to Boston firefighter's death in Dorchester

Investigators say lithium-ion batteries were the cause of a fire that led to the death of a Boston firefighter in May. Firefighter Robert Kilduff Jr. died after he fell from the third floor of a burning home on Treadway Road in Dorchester.

Investigators determined the fire started in the rear of the building on a third-floor enclosed porch and was caused by lithium-ion batteries stored inside of plastic toolboxes. The batteries experienced "thermal runaway," Boston Fire Commissioner Rodney Marshall said at a press conference on Wednesday. 

Marshall emphasized the importance of properly storing and charging the batteries. 

"These batteries must be charged, handled and stored in accordance with the manufacturer's recommendations and established safety guidelines," Marshall said. "Improper charging or storage can create serious fire hazards."

Boston Mayor Michelle Wu said Kilduff "made the ultimate sacrifice" for the city and they are working to honor his legacy and support his family.

"These batteries power so much of our daily lives, but also carry very serious risks," Wu said. "So, we owe it to all our community members to educate our residents about the dangers and how to prevent fires like this one."

The National Institute of Occupational Safety and Health and the Boston Fire Department's Board of Inquiry are both still investigating Kilduff's death. "These investigations will examine all of the circumstances surrounding this tragedy," Marshall said. 

Kilduff, 53, was a third-generation firefighter, a 24-year veteran of the Boston Fire Department and a U.S. Marine Corps veteran.