A man tried to kidnap a female high school student in Gaithersburg early Monday, police said.

The student, from Watkins Mill High School, told police that the man approached her at about 7 a.m. as she walked to a bus stop in the Cider Mill apartment community on Lost Knife Circle. The man told her to “shut up” and tried to put a black bag over her head, the student said, but he ran away after she screamed.

The man was described as black, in his mid-to-late 30s, about 5 feet 5 inches tall, with a medium build, wearing black pants and a black-hooded sweatshirt with a red logo on it, police said.

Police asked anyone with information about the incident to contact them at 240-773-5400 or call 866-411-TIPS (8477).

Watkins Mill High School also posted a letter about the incident.

“Please speak with your son/daughter about this incident and the importance of staying alert, taking headphones out, and making a habit of walking to school with a friend,” the letter, from Principal Carol Goddard, said.