Ann Arbor police are investigating a robbery Sunday night at Subway on West Stadium Boulevard, a police report said.

A man walked into the store, twice asked for change, then told a female cashier to "Give me all the money," when she opened the register the second time, the report said.

The robber grabbed cash from the register and said to the clerk, "Don't call the police. If you do, I have somebody in the parking lot that will shoot you in the head," the report said.

The man stole more than $300, walked out of the store and continued south on the street at about 8:10 p.m., according to the report.

He was described as black, between 5 feet, 8 inches and 5 feet, 10 inches tall, with thinning hair and a beard and mustache, the report said. The man was wearing a faded orange sweatshirt and dark pants.

The employee, who has worked at the store for two years, told police she had never seen him before.