Delta College. (File Photo)

STOCKTON-

Delta College Police in Stockton say a woman was sexually assaulted Tuesday morning.

The student was walking alone at about 10 a.m. in the south stairwell in the Bud Building. A man reportedly grabbed her buttocks and ran down the stairs.

The assault went unreported until 2:15 p.m. Wednesday afternoon, officers say.

The man that allegedly grabbed the woman is described as a black man about 6 feet tall. He was wearing a black jacket and blue jeans, and had a short fade haircut.

A similar assault happened in a stairwell in the Locke Building on April 30, 2012.