(CNN) -- A 6-year-old New Jersey boy has died after being shot in the head by a 4-year-old playmate as their parents stood in the yard nearby, a local police chief said.
Brandon Holt was pronounced dead at 5 p.m. Tuesday at Jersey Shore University Medical Center in Neptune, according to Toms River police Chief Michael Mastronardy.
It was the second incident in the United States in recent days involving young children accidentally shooting others.
Brandon was playing in and around the 4-year-old's Toms River home on Monday evening when the younger child left the yard and went inside, police explained.
"The 4-year-old ... retrieved a rifle within the house, a .22-caliber rifle, came outside," Mastronardy told reporters earlier Tuesday. "... A shot went out and the 6-year-old was struck in the head."
Daniel Watkins, uncle of the 6-year-old boy, told CNN affiliate WCBS that the two children were friends.
"It's really difficult to deal with," Watkins said. "This is something that shouldn't have happened. It's horrible."
A family friend, Lynne Boccadoro, told CNN affiliate WABC that Brandon and his family had recently come over for Easter dinner.
"Always smiling, always laughing," she said of Brandon. "The cutest, cutest little boy."
The Atlantic County prosecutor's office is leading the investigation to determine whether charges will be filed in the case and, if so, against whom, Mastronardy said Tuesday night.
This eastern New Jersey incident follows another fatal shooting days ago that also involved a 4-year-old boy, this time in Tennessee.
Josephine Fanning had gone into a bedroom, along with the boy, where her husband -- Wilson County Sheriff's Deputy Daniel Fanning -- was showing a relative some of the lawman's guns.
At some point, the boy picked up a loaded pistol from a bed and shot Josephine Fanning dead, said Tennessee Bureau of Investigation spokeswoman Kristin Helm.
CNN's Greg Botelho contributed to this report.