Firefighters arriving at the Washington Street row home around 6 a.m. found all three floors "fully involved in fire," Allentown Fire Captain John Christopher said.
Two adults and four children were already out of the house by the time crews arrived, the fire captain said.
The residents were taken by EMS to Lehigh Valley - Cedar Crest for treatment of minor injuries and smoke inhalation, Capt. Christopher said. It is unknown whether any of the victims were burned, but they are likely to live.
However, a family dog did die in the fire, the fire chief added.
The blaze took around 45 minutes to extinguish, as crews were having trouble reaching the third floor, Capt. Christopher said.
There were no injuries to firefighters, and the fire did not spread to any nearby homes.
The Red Cross was assisting the displaced residents.
The cause remains under investigation by the city's fire marshal's office.
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