SAUGUS – State Police are investigating an attack on a 20-year-old female lifeguard at Breakheart Reservation Tuesday afternoon, that left her with potentially serious injuries.Massachusetts State Police Sgt. Byron Rizos told members of the media at a press conference that the lifeguard had been on-duty even though the beach was closed for maintenance. She had gone for a walk in the reservation and was soon after reported missing to the State Police at approximately 2:13 p.m.About an hour later, Rizos said a female jogger heard cries for help in the reservation and, along with a nearby Environmental Police Officer, discovered the woman on a trail at 3:18 p.m.?She was extremely shaken up and had potentially serious injuries,” Rizos said.Saugus Fire Chief James Blanchard said the woman was rushed to Massachusetts General Hospital in Boston with head and neck injuries. He expects her to survive the vicious attack.For now, Rizos said troopers are working to pin down the exact location that the incident occurred, saying only that it was away from the beach area.Clues may lie on surveillance video that potentially captured the incident by nearby Northeast Metropolitan Regional Vocational School. Rizos said the tape is currently being reviewed.?Hundreds of thousands of people enjoy that reservation and they have not had a lot of incidents like this,” Blanchard said. “They do patrol the area and have rangers there. I?m sure this will step up patrols.”Either way, the brazen assault has town residents feeling unsettled.?I come here all the time, sometimes by myself, but I?m not going to do that again,” said Linda Vasapolli. “I can?t believe this happened.”Vasapolli and her husband, John, Saugus Town Counsel, stumbled upon the swarm of media at the entrance to the state park while on their way for an evening walk.?We come about three times a week,” John said. “I jog, she walks, and we usually feel pretty safe. People walk their dogs there, ride their bikes and cook on the grills. It?s a beautiful place.”Melrose resident Ernie Karelas said he believes he saw the lifeguard moments before she was allegedly assaulted near the Wakefield entrance of the reservation.?I walk six days a week in the park, and I saw a lifeguard walking away with a guy and entering the woods,” Karelas said. “There weren?t many people around and I remember what he looks like. I?m going to tell the police what I know because I just want to nail the guy.”The reservation spans 640 acres, which includes two fresh-water lakes and a section of the Saugus River. Rizos said troopers quickly locked down the reservation, set up a perimeter around it and immediately began combing the area with a K-9 unit, numerous detectives and the air-wing.For now, the park will only be open from daylight to dusk as the investigation continues, and to ensure the safety of its visitors.?There haven?t been any assaults (recently) like this in the park,” Rizos said. “It?s very safe.”? Matt Tempesta contributed to this report.