Story highlights Authorities identify the suspected gunman as Shane Schumerth, 28

No students were believed to be involved in the incident

The headmistress killed had worked at the private school for 34 years

The fired employee returned to the school with an assault rifle, authorities say

A fired employee of Episcopal High School in Jacksonville, Florida, returned to the school Tuesday, shot and killed the headmistress and then killed himself, authorities said.

The gunman, who was terminated earlier in the day and carried an assault rifle in a guitar case, went to the office of Headmistress Dale Regan, Undersheriff Dwain Senterfitt with the Jackonsville Sheriff's Office told reporters.

"He shot and killed Ms. Regan and then he killed himself," he said.

The sheriff's office later identified the suspected gunman as 28-year-old Shane Schumerth.

No students were believed to be involved in the incident.

"Our prayers go out to the Episcopal community," Senterfitt said, noting that he knew Regan personally and that his daughter had recently graduated from the same private school. "It's a tough day for us."

Regan had worked at Episcopal High School for 34 years, according to Kate Moorehead, dean of St. John's Cathedral in Jacksonville.

"We have full confidence that Dale Regan is already with God and in heaven," she said. "We ask you to please pray for us as a community."