A pair of brothers are dead after a fatal fire in a Bronx apartment building Thursday night, authorities and sources said.

The deadly blaze started at approximately 10:46 p.m. in a single apartment on the 6th floor of 2700 Grand Concourse in the Kingsbridge section of the Bronx, cops said.

Emergency Responders discovered the two brothers, 49 and 44, unconscious in the burning apartment and rushed them to Montefiore Medical Center and Jacobi Medical Center, where they were each declared dead, authorities said.
The fire was under control less than an hour later, around 11:25 p.m. Three firefighters also suffered minor injuries, FDNY officials said.

The cause of the fire is still under investigation.