SOUTH FORSYTH – Neighbors and residents of Forsyth County were rocked Wednesday when they learned two brothers under the age of 10 were among the four killed in their south Forsyth home in what authorities ruled a murder-suicide.

A total of five people were shot, four fatally, in the domestic violence rampage around 6 a.m. All of the victims were in the same family, and no one escaped unharmed.

The three murder victims include Rebecca Manning, 37, and her juvenile sons, Jared and Jacob Smith. Manning’s 75-year-old father, Jerry Manning, was also shot and remained in critical condition as of Thursday.

Matthew Fields, 32, was the suspected shooter – the only suspect – and died of a self-inflicted gunshot wound. Fields was either Manning’s boyfriend or husband, according to authorities.

The Smith brothers were students at Johns Creek Elementary School, according to Jennifer Caracciolo, spokeswoman for Forsyth County Schools.

Jared Will Smith, 8, was a rising second-grade student, having attended the school since 2012.

Jacob “Jake” Jerry Dean Smith, 9, would have started fourth grade in two weeks. He had been at the school since 2011.

They were both reportedly in bed when they were killed.

Forsyth County Sheriff Duane Piper said the children and the shooter were pronounced dead on scene when emergency personnel arrived to the residence on the 5500 block of Old Atlanta Road. Rebecca Manning died a short time later at the hospital.

Jerry Manning was taken to an area hospital in critical condition from multiple gunshot wounds.

Piper said in a news briefing Wednesday at 10 a.m. that detectives hope to find an official motive during the ongoing investigation.

“There’s no reason we’re ever going to understand why he shot an entire family,” he said.

Minutes before the 911 call came in, a nearby business reported hearing gunshots.

The residence where the shooting occurred neighbors the Olde Atlanta Golf Club, a golf course community of more than 600 homes with properties along the Chattahoochee River.

Old Atlanta Road was shut down from Westminster Lane to the Fulton-Forsyth county line at McGinnis Ferry Road until Wednesday evening, though units remained in the area to patrol the roadway while investigators conducted a search warrant on the home.

According to Robin Regan, a spokesman for the sheriff’s office, a “large support staff” responded to the incident throughout the day, including detectives, crime scene technicians, deputies to assist with traffic, equipment support staff, media and communications deputies and units from Georgia State Patrol.

Because the response required so many people, he said, additional resources from throughout the sheriff’s office “moved around” and filled in for roles to “ensure almost immediately after getting on scene that the rest of the county had appropriate coverage.”

Online editor Jim Dean and staff writer Kelly Whitmire contributed to this story.