A 71-year-old woman was sexually assaulted and her husband, a retired police lieutenant, was attacked with a blade during a brutal home invasion in Brooklyn on Monday, the police said.

The intruders remained at large Monday evening and their motive was unknown, the police said.

The police were called about the attack, on Madison Place, near Marine Park, around 5:30 a.m., said Sgt. Jessica McRorie, a spokeswoman for the New York Police Department.

Three men broke into the home and attacked the couple, she said.

The woman was tied up and assaulted. The man, 72, who is retired from the Police Department, was injured after being struck in the head with a box cutter, the police said.