A 14-year-old boy has been arrested after allegedly killing his parents and severely injuring his 11-year-old sister at their home in a rural community in Fresno County, California, on Wednesday, authorities say.

The suspect, who is not being identified because of his age, originally called the sheriff’s office after the double slaying and told them someone had broken into their house in Miramonte, attacked his family, and fled in a truck, Fresno County Sheriff John Zanoni said during a news conference Friday.

Detectives later noticed inconsistencies in the boy’s story, according to Zanoni.

“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.