Topsham police say a 19-year-old Bath woman could lose an eye after a 16-year-old girl savagely attacked her with a tire iron early Sunday morning.

Sgt. Robert Ramsay said the 19-year-old was staying at a home in Topsham when the 16-year-old girl came there around 5 a.m. and knocked on the front door.

When the 19-year-old answered the door, she was hit in the face with a tire iron. The 16-year-old was arrested later in the day and charged with elevated aggravated assault.

The girl, whose mother brought her to the Topsham police station, was being held Monday night at the Long Creek Youth Development Center in South Portland.

Ramsay said police are still not sure what provoked the attack. The victim told police she does not know why the other girl hit her with the tire iron.

Topsham police were notified at 5:42 a.m. Sunday by Mid Coast Hospital in Brunswick that they were treating the young woman for a serious eye injury. She was transported by ambulance to Tufts University Hospital in Boston, Ramsay said.

Ramsay said the victim’s mother told police that her daughter’s optical bone around one eye was broken and will require surgery. She could lose her sight in that eye and also lose her sense of smell.

Ramsay declined to name the street and address where the assault took place, but said Topsham police have responded to a number of calls for service at that address. The home’s owner, a man in his 70s, allows homeless individuals and people with drug addictions to stay there, he said.

Topsham police are continuing to investigate the circumstances that led up to the attack.