A junior firefighter who was beloved by fellow volunteers at the Harris Hill Fire Company was killed Sunday morning in a one-vehicle crash in Clarence.

Authorities said Alexander E. Hemline, 17, of Clarence, died hours after his northbound Jeep struck a tree along Kraus Road.

Erie County Sheriff’s deputies were trying late Sunday to determine what caused Hemline, a student at Clarence High School, to lose control of his vehicle at about 9:45 a.m.

Hemline was a helpful and enthusiastic junior firefighter with the Harris Hill company, said the volunteer company’s chief, Nick Radlich.

“Alex was a wonderful kid,” Radlich said in an interview Sunday night. “He was extremely helpful, always willing to help out the guys in any way he could. He’s been with us for about a year and a half. He was recruited by one of the ladies in our ladies auxiliary who has known him since he was a baby.”

As a junior firefighter, Hemline could fight fires and take part in all the same activities as full-fledged firefighters, except he was restricted from going into a burning building, the chief said.

After the crash Sunday morning, Hemline was rushed by Mercy Flight to the Erie County Medical Center in Buffalo, where he was pronounced dead.

Radlich said he was at the hospital with Hemline’s family.

“We’re all grieving. He was a brother firefighter,” said Radlich, whose fire company has about 35 members.

The death prompted a number of Facebook posts about the popular teen.

“One of the hardest-working kids I’ve ever had the pleasure to work with,” one teacher wrote. “Your sweet smile and innocence will be missed. Rest in peace, little Alex.”