SILVER SPRING (WJZ) — Investigators in Montgomery County are trying to figure out what sparked a house fire that left a man in critical condition Thursday morning.

The flames broke out early in the morning along the 2300 block of Dexter Avenue in Silver Spring.

Officials said the fire spread after a couch caught fire on the first floor.

A dog died of smoke inhalation.

A firefighter was also hurt but is expected to be okay.

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