BELLEFONTAINE, Ohio -- When the 49 students in Riverside High School's class of 2005 marched into the gymnasium for commencement Sunday, they could not help but notice two empty seats.

Not until the ceremony was nearly complete did they learn classmate Scott Moody was dead. On Monday, students found out the rest of the news, that the 18-year-old was believed to have killed their other missing classmate, his grandparents, his mother and another family friend before shooting himself.

"Everybody was wondering, 'Where are these two kids?"' school superintendent Bernie Pachmayer said Monday. "I think instinctively they knew something was wrong."

Logan County Sheriff Michael Henry said he did not know if authorities would ever determine why Moody acted as he did, "but we're going to try."

Moody also shot his younger sister, who was in critical condition Monday.

The shootings came hours after a family party to celebrate the graduation of Moody and classmate Megan Karus at the farmhouse near this west-central Ohio town were he lived with his mother and sister.

Students who saw Moody early Sunday before the shootings described him as being in great spirits and looking forward to graduation, Pachmayer said.

"In our minds, it couldn't possibly be Scott," she said.

She said he was a clean-cut boy who wanted to farm and fit well into the area when he came to the district two years ago.

"He was a farmer at heart," she said. "He worked the land."

Sometime Sunday morning, Moody went to the neighboring farmhouse and killed his grandparents with a .22-caliber rifle, then came home where he shot the others then himself, Henry said.

Fields where corn and soybeans are grown surround the white-paneled, two-story houses, which are about a quarter-mile apart along a two-lane state highway that runs through this city of 13,000 people, about 45 miles northwest of Columbus.

Lone survivor

Moody's sister and the lone survivor, Stacy Moody, 15, called her stepsister and told her that she and her mother had been beaten up and that she could not wake her mother, Henry said.

Stacy Moody had been shot in the neck. She remained hospitalized Monday at Ohio State University Medical Center.

The stepsister, Nicole Vagedes, went to the house and called 911, telling emergency dispatchers about finding bodies throughout the house. Authorities released a copy of the tape on Monday.

"I can't wake her," she said of the Moodys' mother, Sheri Shafer, 37. "I can't get a pulse."

Vagedes' voice became higher pitched as she found more bodies upstairs, then another in the living room while she was on the phone with the dispatcher.

"Oh my God, there's one in the living room. There's another one on the couch," she said.

Henry said the grandparents, Sharyl, 66, and Gary Shafer, 67, were shot in their kitchen.

The bodies of Sheri Shafer, and Paige Harshbarger, 14, a family friend, were found in upstairs bedrooms of their home, along with the body of Moody himself. Karus, 19, another family friend, was found on a living room couch.

Karus and Harshbarger had stayed overnight following the party.

There was no sign of a struggle at either house, Henry said, adding that it appeared Karus, Harshbarger and Sheri Shafer were killed while they slept.

Henry said the sheriff's office has received nuisance calls about loud music and parties at the house, but he did not know whether the complaints were about Moody.

"It's tough on us," Henry said of the shootings. "We knew these people. We're familiar with these kids. I feel so badly for these families, this community."

Last week, Moody's family had taken out two congratulatory ads featuring Moody's picture in the Bellefontaine Examiner. The ad from his mother and sister read "Good luck and have fun!"

Brandon Stewart, 16, a year behind Scott Moody and Karus at Riverside High School, said students at the small school all knew one another and that everyone got along with the four students who were shot.

"None of them seemed like troublemakers," Stewart said.

The graduation ceremony, already emotional because of a classmate's death a year ago in a car accident, became further subdued when Pachmayer told graduates of Moody's death.

"It was a very somber recess out. There were kids and parents that were crying," she said.