Mesa firefighter Mark Keller was "found passed away while on duty," the Mesa Fire and Medical Department said.

The Mesa Fire and Medical Department is mourning the loss of one of its firefighters who passed away unexpectedly on Tuesday ...

PHOENIX — The Mesa Fire and Medical Department is in mourning after the death of longtime firefighter Mark Keller. Keller was ...

The Mesa Fire Department is mourning the loss of Firefighter Mark Keller. Officials say Keller died Tuesday morning while on duty.

MESA, Arizona — A 35-year-veteran of the Mesa Fire Department died Tuesday morning while on duty. Firefighter Mark Keller, who started with the East Valley agency in 1990, was found deceased during a ...