Thursday marks the four-year anniversary of the deaths of three Pittsburgh police officers.
Pittsburgh Police honored the fallen heroes with a special message on the police scanners.
"A moment of silence will be observed in remembrance of officers Paul Scuillo, Stephen Mailey and Eric Kelly who were killed in the line of duty on April 4, 2009. At 'oh seven six hours' they were dispatched for their final call. Their bravery and dedication will always be remembered," a dispatcher said.
The officers were shot and killed responding to a 911 call from Richard Poplawski's mother's house in Stanton Heights.
Poplawski shot and killed all three officers when they responded. He was convicted of three counts of first degree murder for their deaths. A judge later sentenced Poplawski to death.
Investigators said Poplawski was armed with an AK-47 assault rifle and several other guns.
The officers were the first on the Pittsburgh police force to be killed in the line of duty in 18 years.