A Northwestern student was robbed Thursday night after leaving the Foster Street CTA station, according to a University security alert.

A man and two girls started talking to the student at about 8:30 p.m. in the parking lot of Engelhart Hall, which is adjacent to the station, according to the alert and police. With his hand in a bag, the man suggested he had a gun and demanded the student’s cell phone and money.

The student handed over his cell phone and $20, the alert and police said. The man gave back the cell phone and fled west toward Maple Avenue.

The man never showed a weapon, according to the alert. The student was not hurt.

Evanston and University police looked for the man but could not find him.

On Friday, police released CTA surveillance photos showing the man and two girls leaving the station. Authorities said the girls are between 14 and 16 years old, and the man is 40 years old.

— Patrick Svitek