An 11-year-old boy was fatally shot in the chest by an older brother Monday in Overbrook, police said.

The shooting occurred just before noon in the dining room of the brothers’ home on the 5700 block of Haddington Lane.

Acting Police Commissioner Christine M. Coulter said police took the boy’s 19-year-old brother into custody and took him to the homicide division at Police Headquarters for questioning. No names were released.

“The brother’s responsible,” Coulter said while standing on the quiet block of tidy two-story rowhouses. “Whether it was intentional or accidental, I don’t know. But they were the only two people in the house.”

Police took the boy, who had been shot in the chest, to Lankenau Medical Center, where he was pronounced dead at 12:25 p.m.

At some point after the shooting, the victim’s mother returned to the house and police took her to Lankenau, Coulter said.

Police officers found a handgun in the house, Coulter said.

The boy is at least the fifth child killed by gunfire in Philadelphia in the last month. Two others have been critically wounded.

The latest fatalities include Leslie Woodson-Holmes, who was shot and killed alongside his family, allegedly by his half-brother in West Philadelphia; Nikolette Rivera, who was fatally shot in her mother’s arms allegedly by men gunning for her father; and Damaya Alcindor, 10 months old, and her sister, Maxillie, 4, who were allegedly shot dead by their mother in the Northeast.

A 10-year-old boy was critically injured but survived when he was shot while walking home from school in Frankford, and an 11-month-old boy suffered gunshot injuries when bullets struck him while he was in a car.

“In every instance, it was a gun in the hands of people who shouldn’t have guns,” Coulter said, adding that there was “no excuse” for the guns to be around children.

Neighbors said the family hadn’t lived on the block for long. Residents expressed disbelief and sadness after the deadly shooting.

“Everybody gets along, everybody’s mostly retired,” said Camille Brinkley, adding that she didn’t know the family well. “It’s just kind of shocking to see that happen.… I just feel sad for the family.”

Jerome Kinsey, who lives on nearby Stewart Street, was on Haddington looking toward the yellow crime scene tape that blocked off part of the street.

“Now a little boy lost his life,” said Kinsey, who works in environmental services at Children’s Hospital of Philadelphia. “He hasn’t even begun his life.… A lot of these children [don’t] have a chance to grow up.”