Authorities continue to pursue H1N1 flu as a possible reason why a La Crosse second-grader died Wednesday after collapsing at his home.

An autopsy Thursday at the Minnesota Regional Medical Examiner's Office in Hastings did not determine a cause of death for State Road Elementary School student Cristian "C.J." Ehler, 7, said La Crosse County Medical Examiner John Steers.

Doug Mormann, La Crosse County Health Department director, said Ehler died of "apparent flu-like symptoms" and the autopsy revealed no obvious physical cause of death.

Results from cultures and lab tests are pending, Mormann said, and confirmation of H1N1 could take several days.

A physician saw the boy, the son of Glenda and Tim Ehler, on Wednesday for a fever and pneumonia, according to a letter Principal Dave Gluch sent to parents and staff.

Teachers notified parents of students in Ehler's State Road Elementary class and his brother Josh Ehler's fifth-grade class about the death. The La Crosse School District did not have classes Thursday or today because of a teachers' convention.

Superintendent Jerry Kember said Thursday classes will resume Monday as planned.

"We believe ... students are safe to return to school on Monday," Kember said. "We need to be careful. We believe the school is safe." The school district continues to follow county health department and Centers for Disease Control guidelines, Kember said. That includes increasing its cleaning efforts and available flu-prevention supplies for students.

The numbers of absent students dropped Wednesday to 7.9 percent, which Kember said "during the flu season is pretty normal" for La Crosse's 15 buildings.

Gluch said information is available on the State Road School Web site to help parents talk to their children about Ehler's death and understand their grief.

"He was always smiling, always saying hello and always asking, 'How are you doing, Mr. Gluch?'" Gluch said. "He was just a beautiful boy who will be missed.

"He played with everybody. He was so friendly."

State Road Elementary School is a "big, extended family," Gluch said.

"Our hearts go out to the Ehler family. We're there to support them and do what we can for them and the rest of our students and families."

If confirmed, Ehler's death would be the second in the Coulee Region related to the H1N1 virus, also referred to as swine flu. A 21-month old Cashton girl died of H1N1 flu complications Oct. 11.

As of Wednesday, the state had reported 14 deaths related to H1N1 flu since spring. Seventy hospitalizations due to H1N1 have been reported in Wisconsin since Sept. 1. The state Department of Health Services report showed 65 of 72 counties had confirmed H1N1 cases, and flu activity continued to increase across the state.

The state Department of Public Instruction reported the Omro and Elcho school districts shut down because of flu-like illness until next week. They were joined by eight other individual schools.

Tribune reporters Anne Jungen and Terry Rindfleisch contributed to this story.