Milwaukee police and the family of a 5-year-old girl fatally shot while sitting on her grandfather's lap pleaded for the public's help Saturday in finding the shooter, while also announcing the girl's heart had been donated to help another child.

Police Chief Edward Flynn said he would keep a photo of Laylah Petersen in his chest pocket, next to the photos of his own grandchildren, until suspects are arrested. Laylah was on the couch when one of a dozen bullets fired into her grandparents' home came through a wall and struck her in the head.

"She is going to be in our hearts, like her little baby heart is going to be in somebody else's," he said during a news conference with Laylah's parents, grandparents and other relatives. "We know that as awful as this event has been, she is going to live on and save a life."

No arrests have been made in the Thursday evening shooting. Investigators have said they don't believe anyone in the home, where Laylah was being raised by her grandparents, was being targeted.

Flynn said officers were getting good tips and canvassing the neighborhood for witnesses. He urged anyone with possible information to come forward, saying "at this point, rumors are as helpful as facts."

He said the house may have been mistakenly targeted, but that several theories were being explored. Without elaborating, he said investigators were having some success with physical evidence and were "in a different place today than we were yesterday." Police have said officers found a dozen casings at the scene, and were looking into whether more than one handgun was used.

The chief said his officers "are not going to rest until we find the perpetrators of this vicious crime to justice."

Laylah's relatives tearfully hugged officers during Saturday's news conference, and her aunt, Tracy Martinez, said family was especially grateful to the first officers on the scene.

Family spokesman Richard Schwoegler III said Laylah's heart had been donated. He also urged faith-based organizations to take to the streets in an effort build relationships with troubled people. Flynn said so far 11 children under the age of 13 have been shot this year in Milwaukee, compared to two last year.

A funeral is planned for Wednesday. A reward of up to $5,000 is being offered for information leading to an arrest and conviction in the case.