According to a police report, a call from a security guard prevented sexual assaults in an office building

An office worker was attacked on Cambridgepark Drive in Cambridge on Friday. (Image: Google)

Cambridge police are investigating a reported sexual assault that occurred at an office building on Cambridgepark Drive around 9:18 p.m. Friday. The warning was issued on Saturday afternoon.

Police responded to reports of an ongoing attack by a security guard who regularly patrolled the building. He said he heard screams coming from a floor under construction that scanner reports said was supposed to be empty. The victim may have been working on a nearby floor, where investigators were investigating a restroom crime scene and working with Massachusetts State Police to identify and search for a suspect.

The victim told officers the attacker was a masked man with a knife.

The Middlesex District Attorney’s Office was notified, police said.

Anyone with information about the incident is asked to call (617) 349-3300 or contact anonymously.

Residents should call 911 immediately if they ever feel threatened or see suspicious activity, police said. An earlier attack in the area occurred on June 24, when a woman fended off a so-called flash rape while walking her dog on CambridgePark Drive around 3:30 a.m., police said.