RIVERVIEW, Fla. — A 14-year-old boy is in custody, accused of killing his own mother and shooting her boyfriend multiple times.

According to the Hillsborough County Sheriff's Office, the incident happened Saturday afternoon in Riverview.

Sheriff Chad Chronister said this is "a heartbreaking situation" for the family involved and the neighbors who witnessed it. Investigators said they are unsure why the 14-year-old suspect shot his mother, but said the boy has not had prior criminal history. 

"This family’s lives have been changed forever," said Chronister. "They lost a mother, this mother’s life is over and when I tell you that this is one of nightmares. This is heartbreaking."

The sheriff's office said this all happened shortly after 4 p.m. in the Summerfield subdivision in Riverview. Officials said they received several calls about a shooting and a young man running through the neighborhood waving a handgun.

The suspect's older brother told deputies he heard his mother and her boyfriend arguing, then heard several gunshots. Officials said that's when he left his room and said he saw his brother shoot his mom. 

Deputies said when they arrived on the scene, the woman was dead.

"Our suspect is only 14 years of age. This 14-year-old young boy’s life is over too. He will never see the outside of a detention facility," Chronister said.

Chronister said the boy also shot his mother's boyfriend five times. He was taken to Tampa General Hospital in critical condition.

The sheriff also said when deputies confronted the suspect, he repeatedly threatened to shoot himself and it took deputies 16 minutes to de-escalate the situation.

Investigators said they are waiting on a search warrant to get into the home and figure out exactly what happened.