Commander Thomas Stangrecki of the Pittsburgh police department said some kind of fight broke out in the stands at the field in the East Liberty neighborhood shortly after 10 a.m. Saturday.
One man was shot three times in the chest and a woman was shot in the abdomen, and both were taken to UPMC Presbyterian in critical condition, he said. Another woman shot in the arm was also taken to a hospital.
The game at the field adjacent to the former Peabody High School, now the Pittsburgh Obama International Studies Academy, was between 6- and 7-year-old players from the East End Raiders and a team from Wilkinsburg.
One of the East End coaches, Don Peters, told the Pittsburgh Tribune-Review that people started screaming and scrambling out of the stands as one of the injured women fell down several stairs.
"This ruined everything for 5,000 children" in the youth league, he said.
"I thought it was fireworks -we often do that," Garrett Barnett, coach of the Wilkinsburg team, told the Pittsburgh Post-Gazette. "Everything got real quiet, and then real noisy. Kids were crying, they were all scared."
No suspects were immediately arrested, Stangrecki said.
Commander Sheryl Doubt said, head of the East Liberty police station, told reporters that the gunfire apparently stemmed from an argument the day before in Wilkinsburg that continued on social media overnight, but she didn't know what the dispute was about.
"It doesn't matter to me what it was about," Doubt said. "It was probably something very petty, because that seems to be the trend."