Mesa firefighter passes away while on duty
MESA, Ariz. - Officials with Mesa Fire and Medical Department say they are mourning the death of one of their own.
What we know:
In a statement, officials with the department say firefighter Mark Keller was "found passed away while on duty" during the morning hours of May 6.
"Mark started his career with the department in 1990 and has provided 35 years of dedicated service to Mesa," read a portion of the statement.

Late Mesa Firefighter Mark Keller (Courtesy: Mesa Fire and Medical Department)
What they're saying:
Mesa Mayor Mark Freeman said he had a connection with the late firefighter, while remembering the impact he had on those around him.
"As a retired Mesa Fire Captain Paramedic, Mark and I served together for many years, and I had the privilege of witnessing his dedication to our community firsthand," Mayor Freeman wrote. "I extend my heartfelt condolences to the Keller family, his crew and all members of the Mesa Fire and Medical Department. Mark’s legacy will continue to inspire us all."