State police were investigating the early morning sexual assault of a 24-year-old Boston woman in Cambridge Tuesday.

Police said an assailant riding a bicycle allegedly attacked the woman near the Weld Boathouse on Memorial Drive at approximately 2 a.m.

The woman told police a man approached her on his bike, then physically and sexually assaulted her near the Harvard-owned facility on the Charles River as she tried to walk away.

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When she screamed for help, two witnesses ran toward her and the alleged assailant fled on his bicycle, according to police.

The victim was transported to a nearby hospital and had since been released, police said.

The suspect is described as a white male in his late 20s or early 30s with a stocky build and blonde or light brown hair. No description of the bicycle was available, police told Metro.

As part of the investigation underway, police were determining whether nearby cameras captured images of the attacker, State police spokesperson David Procopio told Metro.

Procopio praised the two witnesses for intervening.

“We’re very grateful that two bystanders heard her call for help and rushed toward her and interrupted the assault,” Procopio told Metro. “They most likely saved her from further injuries.”

Anyone with information is urged to call State Police at 617-740-7875.