A 17-year-old Medfield girl, who disappeared Monday after leaving her hometown’s public library with an unidentified man, is believed to be in danger, according to police.

Brittany Thompson left the library with the man at 4:25 p.m. on Monday wearing a red sleeveless shirt, blue jeans, and flip flops, according to police. She has braces and wears sunglasses on her head often.

Medfield and State Police released an image (left) of the man who is said to be white, heavy set, with slicked-back hair and wearing a “Sons of Anarchy” T-shirt.

Contact the State Police at 508-820-2121 if you have any information.