JACKSONVILLE, Fla. – A 56-year-old grandfather stabbed his adult son and daughter Monday morning and then set their Shirley Avenue house on fire in the Lakeshore area of the city's Westside, according to the Jacksonville Sheriff's Office.

Police and the Jacksonville Fire and Rescue Department responded to the home after reports of a double stabbing and a fire.

Police said a 29-year-old man, identified by neighbors and court documents as Carlos Rivera Jr., heard his 31-year-old sister screaming and found their father stabbing her in the home, which is off San Juan Avenue. The father then stabbed his son multiple times when he started to intervene, according to JSO.

Police have not publicly named the 56-year-old man, but neighbors and court documents identify him as Carlos Rivera Sr. (pictured below from an April 2018 arrest on a domestic violence charge).

Rivera Sr.'s two adult children and his three younger grandsons, who were at the house at the time, ran out of the home and took refuge with a neighbor, police said.

That neighbor told News4Jax that her husband was awakened by pounding on their front door just before 5 a.m.

"They were panicked. She had three kids with her. One had blood all over him. First thing, I got the kids in the house, got them settled," Cathy Jennings said. "They did fall back asleep after about 20 minutes in the house, and then they were normal kids. They wanted to play and run around the house and stuff."

Police said the grandfather then set the home on fire and ran from the house before calling police and turning himself in. Rivera Sr. has been charged with arson and two counts of aggravated battery with a deadly weapon.

Neighbor Eli Brown told News4Jax he knew something was happening when he was awakened by lights on the street.

"I thought that there was a fire, but then all the different trucks with the lights on, it seemed like the whole neighborhood was on fire," Brown said. "I was a little concerned, so I came out, and there was smoke all over the place."

Police said Rivera Sr. was injured and was covered in blood. The three adults were all taken to UF Health with non-life-threatening injuries. The children, who were not hurt, remained at the neighbor's home while the Department of Children and Families was notified, police said.

News4Jax later saw the three boys being taken from the neighbor's house wrapped in blankets. One officer was carrying a child who appeared to be a toddler. DCF took custody of the children.

Another neighbor of the Riveras said Rivera Sr. was acting very strangely Sunday afternoon, riding a scooter up and down the street and staring strangely at people he passed. Even with the way he was acting, King Hargrove said, he never expected what he saw Monday morning.

"I said, 'There’s something wrong with that guy right there,' because you can look at a person and tell when something is wrong with them," Hargrove said. "And I said, 'That guy is up to something,' but I didn’t think he was up to that, though."

Hargrove said he’s thankful the actions Rivera Sr. is accused of didn’t end more tragically.

Rivera Sr. was booked just before 3 p.m. Monday into the Duval County jail, where he's being held without bond, according to jail records. His first appearance is scheduled for 9 a.m. Tuesday.

Neighbors said the family had moved into the home in the last few months, and News4Jax found court records that indicate family trouble: