A man died in a townhouse fire in the Alexandria section of Fairfax County early Thursday morning, authorities said.

Firefighters responded to the blaze in the 6900 block of Deer Run Drive around 4 a.m., the Fairfax County Fire Department said. Firefighters found fire and smoke coming from the front, side and rear of the three-story home, which was an end unit.

The size of the fire prompted a second alarm. Over 50 firefighters battled the blaze for 50 minutes, before it was brought under control, the department said. The home was a total loss.

Both police and fire investigators are investigating how the fire started, and the cause of the man’s death, but the medical examiner will make a final determination on that. The man’s name is being withheld pending notification of the next of kin.

“There’s no indication that there’s anything suspicious,” said Dan Schmidt, a Fairfax County fire department spokesman.