The 4-year-old boy who fatally shot his 2-year-old brother with a pistol in an upstairs bedroom had found the gun tucked under a pillow.

Kao Xiong, 33, who appeared to be overcome with grief, said in an interview that he had a permit to carry the semi-automatic handgun, and had wedged it under a pillow next to the bed’s headboard.

“My heart is broke,” said Xiong. “I wish I could be a new person.” His wife, Ma Vang, who sat nearby and speaks little English, looked on but had no comment.

Xiong said he worked for a St. Paul non-profit that helps the mentally ill and had come home for lunch. His wife was vacuuming so Neegnco Xiong, 2, and his 4-year-old brother went upstairs and were playing in the bed.

The couple heard a single gunshot and rushed upstairs to find Neegnco hunched on the bed, face down, Xiong said. He told his wife to call 911, picked up the toddler and then spoke to a dispatcher, while he intermittently gave the the boy CPR.

“I can’t imagine this terrible thing would happen to me,” Xiong said. He said he bought the gun a year and a half ago at a sporting goods store and had taken classes and gotten a permit. He said he kept the gun loaded because he sometimes carried it with him, if he went to a store at night or went jogging. Police interviewed Xiong on Wednesday.

Sgt. William Palmer, a Minneapolis police spokesman, called it a "horrible accident" but said an investigation is being conducted and the findings will be turned over to the Hennepin County attorney's office.