Firefighters were dispatched to a rowhouse on the 6000 block of Trinity Street around 4:30 a.m., multiple outlets report.
There, two people were treated for injuries and transported to a nearby hospital, fire officials said. Five others were displaced by the blaze, they added.
Multiple media reports later identified one of the injured as an 8-year-old boy. CBS News reports that the other victim was his 1-year-old brother. Their conditions were not immediately clear Wednesday evening.
Fire investigators are treating the case as arson, it is widely reported. Officials believe the arsonist lit a nearby car on fire before setting one of the houses alight, according to reports.
Philadelphia Fire Department could not be immediately reached for comment.
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