Flags are flying at half-staff and grief counselors are at Westfield High School Tuesday after the sudden death of the school's very popular principal.

Westfield High School Principal Derrick Nelson died Sunday night.

Parents were notified in February that Dr. Nelson, a 20-year army veteran would miss several weeks for a medical issue.

"He did everything he could to make the school a better place in the world, a better place and he always tried to lift people up instead of bringing them down and even though he was in an authoritative position, he was always there for support rather than discipline even though that was part of his job,” said Westfield student Bella Conway.

According to a Facebook post, Dr. Nelson was donating stem cells to a 14-year-old boy in France whom the principal apparently had never met.

In the post, it was written that the surgery did not go as planned.

There's no official word if that surgery is what led to his death.

The superintendent said in a letter to parents that there would be counselors on hand in the morning for students.

Westfield Mayor Shelly Brindle wrote in a Facebook post, “This is a tremendous loss for our community and I know that our children, and we as parents, will struggle with coming to terms with this over the coming days and weeks. He was a man of immense character and kindness and his legacy will live on in the generation of students whose lives he touched.

Besides his work in education, Nelson had served as an officer in the Army Reserve for more than 20 years and had recently re-enlisted. His military service included an assignment in the Middle East. He was the father to a 6-year-old girl.

Funeral arrangements have not yet been announced.

The Associated Press wire services contributed to this report.