The victims were Emily Marie Bivens, 25; Cullen Bivens, her son, who was 14 months old; and her mother, Joan Bernard, 62, according to the sheriff’s office, which also confirmed that Mr. Bernard , the suspect, is the brother of Ms. Bivens.

Officials said that they were still trying to determine a motive and that autopsy results would not be available for several days .

In a news conference on Tuesday, Sheriff Mike Taylor of Pittsylvania County said his office received a call around 8 a.m. from a person who believed that someone in the neighborhood had been shot.

“Officers responded and they did find, in the driveway of a home, a deceased female,” Sheriff Taylor said. “We determined that there are three victims in this case: one child and two adult females.”

On Tuesday morning, public safety officials warned Keeling residents to be on the lookout for a man they identified as Matthew Bernard. “He is armed with a rifle and considered very dangerous,” Pittsylvania County’s public safety department said on Facebook.