BERWICK, Maine (AP) — 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 Friday the cause of the fire that killed Capt. Joel Barnes March 1. 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.

(Information from: Portland Press Herald, http://www.pressherald.com)