Two teenage girls were sexually assaulted in Philadelphia on their way to school in separate incidents this week after they had just used the region's public transit system, authorities said Friday. 

The first attack occurred Thursday at about 8 a.m. when a 15-year-old girl was on a SEPTA train and a male tried talking to her, the Philadelphia Police Department said.

When she got off at the 8th Street stop on the Broad Ridge Spur, investigators say he followed the victim, Fox Philadelphia reported. The suspect then attempted to sexually assault her under a staircase, police said. 

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Philadelphia sexual assault

Philadelphia police said a male captured on security video sexually assaulted a 15-year-old girl on her way to school Thursday morning.  (Philadelphia Police Department)

She got away, and he followed her on to the street where he got her into an apartment and sexually assaulted her, authorities said. 

He is described as a man in his early 20s, about 5-feet-8-inches tall with a slim build, braided hair and a beard. 

The second incident occurred at 8 a.m. Friday when a 13-year-old victim exited the subway at Broad and Race streets when she was approached on the street by a male.

He told the victim he had a gun and forced her into a parking garage stairway and sexually assaulted her, police said. After the alleged assault, he walked the victim toward her school. 

Philadelphia sexual assault suspect

A male suspected of sexually assaulting a teen girl Friday morning in Philadelphia is being sought by police.  (Philadelphia Police Department)

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The police department has not ruled out that both assaults may have been committed by the same person, but investigators have not found evidence that the incidents were connected.