A female Northwestern graduate student walking home early Sunday morning near the Chicago Campus was robbed by a man wearing a ski mask and carrying a knife, police said.

The student was walking south on the 800 block of North Lake Shore Drive at about 12:30 a.m. when a man got out of a four-door, dark-colored van and approached her, said Cmdr. Darren Davis of University Police Chicago. There were two other men in the van.

“Get in the car; I’m going to rape you,” Davis said the man told the student.

After a struggle the man took the student’s purse, which contained only identification cards, and jumped back in the van, Davis said. The student, who ran home and called police, was not harmed.

“But after an incident like that, anybody would be shaken up,” Davis said.

The student could describe neither the man who robbed her nor the men in the van, Davis said. She also could not give police the van’s license plate number.

“Other than taking the report, we have no real leads,” Davis said. “It’s still an open case.”

The student was walking between two buildings during the robbery, which was a block and a half from campus, Davis said.

UP has posted crime bulletins around Chicago Campus and on NU’s Web site highlighting its 24-hour security escort service.

“We advocate (that) students don’t walk home alone,” Davis said.