Police in Portland are urging residents to be vigilant as they try to track down a suspect involved in an attack.

Police said Thursday they responded to the attack around 9:40 p.m. Wednesday on Gray Street. A female victim told them she had been punched several times in the face and head while she was out walking. She fell to the ground and told police the suspect continued punching her before leaving the scene in an unknown direction.

The suspect was described as a white man with a slim build, between 5’5″ and 6′ tall. He was wearing dark clothing and possibly a ski mask and hood.

Police are urging residents to stay alert and try to stick to well-lit areas. They’re asking anyone with information about the attack to contact them.