Three were killed after being forced to kneel against a wall and then shot in the head at close range Saturday night, police said. A girl was found slumped near some bleachers 30 feet away, a gunshot wound to the head but still alive.

The four Newark residents were to attend Delaware State University this fall. No arrests had been made by Monday and authorities had not identified suspects.

Family friend Cathy Rainey, left, holds up a 2006 photograph in Newark, N.J., Monday Aug. 6, 2007, of Iofemi Hightower, 20, and Terrance Aeriel, 18, as Shalga Hightower, right, talks about her daughter, Iofemi, who was killed, along with Terrance Aeriel in an execution-style shooting of four young friends in a schoolyard late Saturday night.[AP]

The shootings ratcheted up anger in New Jersey's largest city, where the murder rate has risen 50 percent since 1998. The high number of killings have prompted billboards in the downtown area that scream, "HELP WANTED: Stop the Killings in Newark Now!"

"Anyone who has children in the city is in panic mode," said Donna Jackson, president of Take Back Our Streets, a community-based organization. "It takes something like this for people to open up their eyes and understand that not every person killed in Newark is a drug dealer."

The killings bring Newark's murder total for the year to 60, and put pressure on Mayor Cory A. Booker, who campaigned last year on a promise of reducing crime.

Jackson said Booker "doesn't deserve another day, another second, while our children are at stake."

Booker said Monday that it was "not a time to play politics and divide our city." A $50,000 reward was being offered for information leading to the arrest of those involved, he said.

A month ago, Booker and Police Director Garry McCarthy announced that crime in the city had fallen by 20 percent in the first six months of 2007 compared to a year ago. Yet despite decreases in the number of rapes, aggravated assaults and robberies, the murders have continued.

Natasha Aeriel, 19, was listed in fair condition at Newark's University Hospital. Police identified her slain companions as her brother, Terrance Aeriel, 18, Iofemi Hightower, 20, and Dashon Harvey, 20.

Authorities believe the shootings were a random robbery committed by several assailants and that some of the victims may have tried to resist their attackers. They were piecing together details of the attack from interviews with Natasha Aeriel.

Hightower and the Aeriels had been friends since elementary school and played in the marching band at West Side High School. Terrance Aeriel, known as T.J., took Hightower to the school prom in 2006, chauffeured by his sister.

At Delaware State they met Harvey, another musician, and struck up a friendship. Friends and family members said the four were not involved in drinking, drugs or gangs. They liked to congregate at the school, which sits in a middle-class neighborhood less than a mile from the campus of Seton Hall University, to hang out and listen to music.

Harvey's father, James, said Monday the parents of the assailants were to blame.

"If you raised your kids better, this would not happen," he said.

Hightower worked two jobs and recently enrolled at the school. One of her jobs was at Brighton Gardens, an assisted living center in nearby West Orange, where her mother also worked.

On the afternoon of the killings, she told her mother she planned to spend the night at Natasha Aeriel's house near the Mount Vernon School.

"The last time I heard her voice was Saturday night," Hightower said between sobs. "She called me from work to let me know Natasha was going to pick her up and she was going to spend the night. She told me she loved me."

The Aerials' mother, Renee Tucker, said the last time she saw them was around 10:30 p.m. Saturday, when they told her they were going around the corner to get something to eat.

"They said they were going to come right back to the house," Tucker said.