A 15-year veteran of the Toronto Fire Service died Thursday in a cycling accident at Kelso Conservation Area in Milton, according to a union representative.

Sara Rosen, 38, was killed when she went off a cliff at about 10:23 a.m., falling about 20 to 24 metres.

She was a "well-respected" member of Toronto Fire Station 443, near Islington Avenue and Eglinton Avenue West, according to Damien Walsh of the Toronto Professional Fire Fighters Association.

"Sara was a very passionate firefighter," Walsh said, adding she was "very passionate about a number of other causes and an active member in our association."

"She really worked tirelessly for firefighters and her community," he said.

She was also an organ donor, according to a tweet the union sent about this time last year, commending her earlier donation of a kidney to her brother.

The union and fire department both expressed their condolences online.

"We lost a sister today," said union president Frank Ramagnano, who lauded Rosen's many charitable efforts within the close-knit community of Toronto's firefighters.

"She was always helping. That's the only way to describe her," he said. "Sara came out to anything to help people — be it cancer, our fundraising, our food drives, she was there."

Rosen was also preparing to take time off work to attend law school, he added.

Sara Rosen - in our hearts and minds. Our sincerest condolences to Sara's family & friends. <a href="https://twitter.com/hashtag/Toronto?src=hash">#Toronto</a> <a href="https://t.co/VspU1UIlNr">pic.twitter.com/VspU1UIlNr</a> —@TPFFA

Emergency crews worked through the evening to recover Rosen's body, which was removed at about 9 p.m.

Officials closed the Kelso Summit and all 16 kilometres of its trails following the incident, while the rest of the area remained open.

"In these situations, our first thoughts are always with the family," said Norm Miller, communications manager for Conservation Halton.

Miller declined to provide details of the incident. Police are investigating.