A masked man crept through the window of a Gaithersburg home, sexually assaulted the woman living there and then fled early Wednesday, Montgomery County police said.

The assailant entered home through a ground floor window on Goodport Court, officials said. The victim called police, who arrived about 2:50 a.m.

The suspect was described as a white male about 5’6” or 5’7” tall, with a thin build. Anyone with information is asked to call Montgomery County police at 240-773-5070.