Pittsburgh police are looking for people involved in a shootout that wounded three people, one critically, on a pedestrian bridge near Stargell Field in Homewood.
Harper said if police do not get the names of the people involved by 8 p.m. Monday, the program will be stopped.
"We aren't going to tolerate this violence any longer in these neighborhoods," said Harper. "If we don't have the names by the end of the day, I'll very seriously consider canceling football in the city of Pittsburgh."
Several local police officers, politicians and community members attended Monday afternoon's news conference. Parents said they are aware of a lot of illegal activity including drinking, drug use and betting at the sight of the shooting. Many parents said they have tried to stop the activity before, but there was "no communication."
Monte Robinson, the president of Homewood Community Sports said he's worried about the league.
"We don't want a few bad apples to ruin it for 300 kids," said Robinson. "It would be a devastating blow."
Channel 11's Renee Kaminski has found out that people were betting on the little league football game when shots rang out at about 3:45 p.m. Sunday. Police have not said if the wagering led to the shooting.
None of the children playing football or any spectators at Stargell Field were hurt.
Police said the shooting happened on a bridge over the Martin Luther King Jr. East Busway, a short distance from the field. Police and witnesses said about 20 shots were fired.
Police Cmdr. Scott Schubert said two men, ages 52 and 38, were wounded, one in the calf and one in the arm who was able to walk away and call medics. Both are in stable condition.
A 51-year-old woman shot in her leg was taken to a Pittsburgh hospital in critical condition.
A police officer driving near the field said he heard the shots first and called for backup.
"He saw a group up on the bridge and then heard approximately 20 shots and turned around and called it out, and various units arrived," said Pittsburgh police Cmdr. Scott Schubert.
Police aren't releasing the names of the victims. No arrests have been made, and police aren't releasing a motive.
Coach Ayodeji Young's little league football team was playing at the time of the shootings. He said little league games are one of the biggest activities for youth's to participate in, in Allegheny County.
"Support is outrageous. People were spilling out the stands it was so packed up here," said Young. "We were winning 6 nothing when the incident occurred."
He said the game turned into chaos when the gunfire erupted and many of the children left in shock. But Young also said that it will not prevent his team from continuing to participate in the sport.
"It's like a festival every week; so many people come out to enjoy it. It's unfortunate what happened, but after this some changes will be made. Security will be tightened," Young said.