CRANDON, Wis. -- Members of a northern Wisconsin community are reeling and in search of answers as authorities investigate a weekend shooting that left seven young people dead and one wounded.

READ: Examine Profiles Of Crandon Shooting Victims

Flags were flying at half staff at the local high school and grief counselors were on duty to help people cope with the tragedy in which a 20-year old Forest County sheriff's deputy killed the six and critically injured another at a pizza and movie party early Sunday morning. The suspect, Tyler Peterson, was later shot and killed by a police sniper.

A special church service was held this morning to pray for the victims. More than 100 people, mainly teens, gathered at a Crandon church on Monday to seek comfort in the wake of the shooting.

Pastor Bill Farr at Praise Chapel Community Church said that a dozen counselors are available to anyone who wants to talk.

Farr said that many who showed up were tearful and that expressing that sorrow or anger is part of the healing process. Farr said that his son grew up with two of the victims and the suspect and they would hunt and fish together.

Authorities Piece Together Incident

The state Department of Justice has taken over the investigation and Attorney General J.B. Van Hollen held an afternoon news conference, WISC-TV reported.

Van Hollen said that the investigation has determined that Peterson, who was also a part-time officer for the Crandon Police Department besides being a deputy, was the sole shooter.

He said that they believe Peterson, who was off-duty at the time, was apparently at the party and got angry after a dispute with his girlfriend. He left, but returned and began firing after retrieving the weapon from his truck. Authorities said that Peterson fired 30 shots in a duplex at about 2:45 a.m. on Sunday morning. The weapon used was an AR 15 rifle, WISC-TV reported.

Law enforcement said that Peterson had dated one of the victims on and off.

Van Hollen said that after Peterson left the apartment, he fired numerous rounds at a responding Crandon police officer. That officer was injured by flying glass.

He said that after Peterson fled, he spoke with the Crandon police chief by phone and confirmed to the chief that he was the shooter. Peterson was located in a residence in Argonne, north of Crandon, hours later and exchanged shots with law enforcement officers. Van Hollen said that is when Peterson was shot, but the cause of his death is still under investigation.

Forest County District Attorney Leon Stenz said that he tried to negotiate with Peterson by phone to get him to surrender.

The victims, who ranged in age from 14 to 20, were gathered at the residence for a late-night pizza party after celebrating the high school's homecoming weekend. The victims who were killed have been identified as Lindsey Stahl, 14, Bradley Schultz, 20, Jordanne Murray, Aaron Smith, Leanna Thomas and Katrina McCorkle.

Autopsies were scheduled on all of those who died, including Peterson, WISC-TV reported.

The lone survivor of the spree was in critical condition on Monday morning, but was later upgraded to serious condition. Charlie Neitzel, 21, of Pickerel, is being cared for at St. Joseph's Hospital in Marshfield.

Friends, Family Recall Victims

Sally Maxon, whose daughter had been best friends with Murray since kindergarten, said that Murray loved children and hoped to be a day care provider.

Derek Dehart said that Smith was a happy-go-lucky guy, who embraced his nickname "Chunk" and almost always had a smile on his face.

Sjana Farr said that Leanna Thomas sang along with her identical twin Lindsey in a church choir.

Sophomore Shelby Votis said that she and her classmates are determined to overcome the tragedy.

"It is going to be really hard, but we are really close so we'll just work with each other and help each other out the whole time," she said.

The school district canceled school on Monday and Tuesday, but classes will resume on Wednesday. Three of the victims were recent graduates and three others still in high school, WISC-TV reported.

Dr. Richard Peters, Crandon School District superintendent, said that opening the school again might be of benefit.

"Experts tell us that returning to some type of normal as soon as possible is very important to helping our children begin the healing process."

Rose Gerow, aunt of victim Bradley Schultz, said that the crime is so senseless because they were friends. Peterson attended high school with them.

Shooter's Family Expresses Shock

Peterson's parents issued a statement through Farrr, their pastor.

The Petersons told the victims' families that they are shocked and feel a tremendous amount of guilt and shame.

"Like those close to Tyler, we are in shock and disbelief that he would do such terrible things," the statement said. "This was not the Tyler we knew and loved. We do not know how to act. We want to express our love and support to everyone effected, but are unsure what would be appropriate. We are hurting for all of your losses as well as ours."

"We are very sorry for what has happened," the statement said. "This tragedy has deeply affected everyone, including us. We also feel a tremendous amount of guilt and shame for the horrible acts that Tyler committed."

Earlier in the day, Peterson's father, Steve Peterson, said that nothing the family can say about his son now would be believable to most people.

Crandon is a very small town of about 2,000 people about two hours north of Green Bay and about 25 miles east of Rhinelander. It's in an area known for logging, and fishing, hunting and snowmobiling. It's also home to the World Championship Off-Road Races.