One of two young sisters who fell from the 4th floor of a Pennsylvania apartment building has died.

The Lehigh County coroner's office says 3-year-old Tamara Arnette died Friday night, shortly after she and her 5-year-old sister tumbled from the window of an apartment building in Allentown.

The older girl is reportedly in critical condition.

The girls fell from a window shortly before 8 p.m. Friday. Exactly how the fall happened remains under investigation.

Allentown is about 50 miles north of Philadelphia.