A 14-year-old California boy who told police an intruder attacked his family has been arrested on suspicion of killing his parents and severely wounding his 11-year-old sister, authorities said Friday.

The boy is suspected of killing his father, Lue Yang, and mother, Se Vang, both 37, at the family’s rural home near the Fresno County community of Miramonte on Wednesday, county Sheriff John Zanoni said at a news conference.

He was being held at juvenile hall, the sheriff said. His name wasn’t released because he is a minor.

The boy’s sister underwent emergency surgery for critical injuries but was expected to recover, while his 7-year-old brother wasn’t attacked and was in the care of relatives, Zanoni said.

The boy made a 911 call claiming that his family was attacked by someone who broke into the home and then fled in a pickup. But detectives found “inconsistencies” in his story and also determined that the victims were attacked using weapons found in the family home, the sheriff said.

“Evidence ultimately showed that he had fabricated the story of a break-in and was responsible for using multiple weapons to attack his mom, his dad and his sister,” Zanoni said.

He didn’t provide other details.

“The tragedy of the situation is of such a high magnitude because two children have lost their mother and father due to the actions by their other sibling,” Zanoni said.

Investigators have not determined a motive, and the investigation is ongoing.

“We haven’t seen anything related to contact with law enforcement, mental health or anything that would lead us to believe that he had a tendency to violence,” Zanoni said.