In this June 11, 2017, photo provided by Erin Thomas, Berwick Fire Capt. Joel Barnes pulls a ladder on the scene of a structure fire in Somersworth N.H. Barnes died on March 1, 2019, while battling an apartment house fire. Credit: Courtesy of Erin Thomas | AP

BERWICK, Maine — The state fire marshal in Maine says an apartment fire that killed a fire captain in March was started by improperly discarded smoking materials.

The fire marshal’s office announced the cause of the March 1 fire that killed Capt. Joel Barnes on Friday. Barnes died after becoming trapping in a third floor room in the Berwick building.

The Portland Press Herald reports investigators were unable to conclusively determine who discarded the smoking materials that caused the fire. Fire Marshal Joe Thomas says no charges are expected.

Barnes was believed to be the first firefighter to die in a fire in Maine in almost 40 years. He was fatally injured while shielding a colleague from flames. About 2,500 people attended a service to honor Barnes in Portland on March 10.