A 25-year-old Whitmore Village man is in custody after allegedly assaulting his sister’s boyfriend with an 18-inch metal pipe, police said.

Kamana Magaoay was charged Monday with attempted second-degree murder and remained at Oahu Community Correctional Center on Tuesday, unable to post $100,000 bail.

The victim, a 24-year-old man, told police he was asleep at his girlfriend’s home at about 1:15 a.m. Friday when Magaoay began striking him with the pipe, a police affidavit filed in Honolulu District Court said.

He later told police he didn’t know why Magaoay was assaulting him. Police said the victim sustained multiple lacerations and fractures to his body and was taken to Wahiawa General Hospital in serious condition.

An officer responding to the scene found Magaoay sitting in a chair in front of the home and Magaoay’s sister standing on the front landing, yelling and pointing to her brother. Magaoay and his sister live in the home with their grandparents.

The officer detained Magaoay and went inside, where he saw the victim sitting on a bed with his face covered in blood, lacerations to his face and right hand, and swelling on his mouth, foot, nose and right forearm.

Magaoay’s sister told police that she was sleeping when her brother pulled a blanket off her and her boyfriend, then began assaulting him and shouting, “I’m going to kill you!” The sister told police she took the metal pipe from her brother .