Counselors were on hand Monday to comfort mourning students as classes resumed at a high school after its "impossible to replace" band director, a student teacher and three others returning from a marching band competition were killed in a bus crash.

Band director Douglas Greenhalgh, 48, his wife, Therese, 51, and their 11-year-old granddaughter Morgan Greenhalgh, were killed early Sunday, along with bus driver Paul Rasmus, 78, and student teacher Brandon Atherton, 24.

Greenhalgh taught at Chippewa Falls High School (search) for more than 20 years, school superintendent Mike Schoch said at a news conference Monday.

"He has created a program that is second to none. He made, like most teachers do, lasting connections with kids. He will be hard to replace, impossible to replace," he said. "It is going to be really hard for somebody to come in and fill those shoes."

The accident happened early Sunday when the bus hit a tractor-trailer that had jackknifed on Interstate 94 northwest of Osseo, said Capt. Douglas Notbohm of the Wisconsin State Patrol (search). Twenty-nine other people were injured, some seriously, troopers said.

"I don't know how much opportunity there was for braking action," Notbohm said. "I don't believe there was much time for the bus driver to react to a total, dynamic lane closure in front of him."

Band members were happy that their band's routine, "Robin Hood: Prince of Thieves," had placed third in its category Saturday at the Wisconsin School Music Association State Marching Band Championships in Whitewater, said Tania Richter, 17, a clarinet player. Nearly everyone was sleeping at the time of the crash, she said.

Schoch said the team had stayed Friday night in Whitewater, some 200 miles from Chippewa Falls (search). He said it was common to return late Saturday from such a trip so everyone could be home on Sunday. Both Chippewa Falls and Osseo are near Eau Claire in the west-central part of the state.

At least 400 students and parents met at the school of about 1,500 students Sunday to get information on the accident. Counselors and clergy were there "to address their spiritual needs," Schoch said.

The school's principal, Jim Sauter, said the school's crisis intervention team would be available for students Monday. "In my career, I have never encountered a tragedy of this degree," he said.

Two students and four adults remained hospitalized Monday with injuries such as broken bones and punctured lungs, Schoch said. All are expected to recover, he said. Other students with minor injuries were treated and sent home.

Schoch said the bus was the first of four carrying about 200 students and 40 adult teachers and chaperones. Notbohm said the bus involved in the crash had a capacity of 53 but he did not know how many were actually on the vehicle.

The tractor-trailer driver, who was employed by Whole Foods Market Group of Munster, Ind., was en route from Indiana to Minneapolis-St. Paul, Notbohm said. He said the driver was hospitalized with non-life-threatening injuries.

It was not known what caused the truck to go off the road, but the driver told investigators at the scene that he had not fallen asleep, Notbohm said.

"We haven't ruled out anything as it relates to the driver's situation," he said.

The National Transportation Safety Board will be involved in the investigation, Notbohm said, and will look at the vehicles and the records of both drivers.

Terry Tauger said his 16-year-old daughter was in one of three buses not involved in the crash. It's been a day of "lots and tears, lots of disbelief, a lot of hugging and relief that most of their friends were OK," he said.