The Cumberland County Sheriff’s Office is investigating a Sunday night home invasion in Casco that left one man hospitalized.

The residents at 19 Timbuktu Drive told deputies that someone knocked on their door at 6 p.m. When the male resident, Walter Knight, 31, opened the door, he was attacked.

A man described as between 6-foot-2 and 6-foot-4 inches tall and wearing a black trenchcoat, burst through the door and started beating up White, punching and kicking him and causing serious injuries, the sheriff’s office said. The woman was uninjured.

The residents said they did not recognize the man and that he did not steal anything, leaving the motive for the attack a mystery.

Knight was taken to Maine Medical Center with serious facial and shoulder injuries, the sheriff’s office said. He is in satisfactory condition, according to a hospital spokeswoman.

The attacker was further described as a white man, 25 to 35 years old, with brown hair and a neatly trimmed beard and moustache.