Manheim Township police charged two Columbia teenagers Thursday with beating and robbing another teen last month at an East Petersburg home.

Also this week, township police charged a local teen with groping a female classmate in a hallway at Manheim Township High School. That teen — a 17-year-old boy — was charged Wednesday with indecent assault for the May 9 incident.

The crimes are not related and involved separate parties, police said.

In the case of the May 26 robbery, the two charged teens, both 17 at the time, allegedly assaulted a 16-year-old East Petersburg boy at a home in the 2000 block of Graystone Road.

The victim and defendants were part of two separate groups gathered at the home, police said. No parents were present at the time, police said.

Everyone at the gathering knew one another, police said. The accused robbers became engaged in a verbal dispute with the victim before the situation escalated.

The robbers' "anger was directed toward him. The verbal argument was with him. Then it just got out of control," Manheim Township police spokesman Sgt. Tom Rudzinski said.

When the two groups began to fight, police said the charged Columbia teens pulled a knife and brass knuckles. The weapons weren't used, but many of the teens ran when they were shown, Rudzinski said.

They stole his backpack, which contained a Sony PSP video-game system, cash and other personal items, and fled in a vehicle, police said.

The victim was left on the ground with bruises and cuts. It was unknown Thursday if he had been hospitalized.

Several minutes after the beating, the attackers came back to the house in the vehicle. Police say a third person, Joshua Zinc Sr., 19, of Columbia, got out of the car and threw a brick through a window of the home.

Zinc has been charged with criminal mischief.

The accused robbers are charged with robbery, reckless endangerment, simple assault, theft and criminal conspiracy. Both were awaiting hearings at Lancaster County Youth Intervention Center at press time Thursday.

In the indecent assault case, the 17-year-old accused was arrested and charged Wednesday.

He was an acquaintance of the 17-year-old female victim, police said.

The boy allegedly forced the girl against a wall in a hallway of Manheim Township High School and "groped" her, Rudzinski said.

Other students were in the hallway and scared off the boy when they tried to intervene.

The victim immediately notified school officials of the alleged assault.

Police didn't identify either teen or provide details on the assault because of the nature of the incident.

"She was trying to get away," Rudzinski said. "You just can't walk up to somebody in a hallway and expect to be given liberties like that."

Rudzinski said in-school sexual assaults are out of the ordinary.

"We normally don't get it in the hall, in the middle of the day, at a school," he said. "That is rare occurrence."

E-mail: bhambright@lnpnews.com