A female victim was sexually assaulted after being robbed at knifepoint while walking down an Oakland street Monday morning, police said.

Police received a report of a female walking in the 9000 block of Holly Street at 6:56 a.m. when she was approached by a stranger from behind who grabbed her and forced her against a gate, according to police.

The suspect held the victim at knifepoint and demanded money. She complied, and then the suspect sexually assaulted her and ran from the area, police said.

The suspect was described as an African-American male standing about 5 feet 6 inches tall with a slim build, weighing between 140 and 150 pounds. He has brown eyes and was wearing a black beanie ski mask, a black hooded sweater and faded black jeans with white shoes, according to police.

Oakland Crime Stoppers offered a $2,500 reward for information leading to an arrest and conviction in the case.

Anyone with information was asked to call the Oakland Police Department's Youth and Family Service Division at (510) 238-3641 or the tip line at (510) 637-0298.