The blaze broke out in the 200 block of South Main Street at 1:21 a.m., according to the York County Department of Emergency Services.
The firefighter was taking to the hospital for dehydration but has since been released, fire officials said.
Two units were damaged and the three residents have been assisted by the Red Cross.
The units will be repaired, although the estimated cost of damage was not immediately available.
The cause of the fire remains under investigation.
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