Philadelphia police are on the lookout for a gun-toting thief who snuck into a Drexel University building and gave a female employee the scare of a lifetime.

The robber made his way into Stratton Hall at 32nd and Chestnut streets shortly after 6 p.m. Thursday and soon wandered into a faculty member's office, said Capt. Benjamin Naish of Southwest Detectives.

The unidentified employee screamed when she saw the man, who was clutching a handgun. "He told her to shut up, and then there was a slight struggle," Naish said. "The victim did not, however, suffer any serious injuries."

The crook made off with the woman's cell phone, but his face was captured on several Drexel security cameras. Naish described him as a thin, 6-foot to 6-foot-3 mustachioed black man in his 20s who wore a distinctive long-sleeved white shirt that appeared to have an image of a mime on it.

Dominic Ceccanecchio, Drexel's senior associate vice president for public safety, said the university is asking its students and faculty to remain on alert. School officials have shared video images of the suspect with security officers at Drexel and the University of Pennsylvania.

"We hope that we get a positive outcome in the near future," Ceccanecchio said. *