WASHINGTON – Investigators say the man found dead inside a D.C. apartment on Isherwood Street intentionally set the fire that killed him.

His death has been ruled a suicide.

Firefighters found Christopher Christofi, 46 of D.C., while battling the blaze on June 4.

The fire destroyed the apartment and damaged neighboring structures in the 1600 block of Isherwood Street NE. Fire crews were called to the building after a report of an explosion.

Neighbors also described what sounded like an explosion, which could be heard from blocks away.

The Office of the Chief Medical Examiner, which ruled Christofi’s death a suicide, said he died of thermal body burns and inhalation of “products of combustion.”

D.C. police say it was Christofi who intentionally started the blaze.

WTOP’s Andrew Mollenbeck contributed to this report. Follow @WTOP on Twitter and on Facebook.