A fifth officer survived the attack. He can be seen outside of the car scrambling to safety during the gunfight which lasted for more than 55 seconds.
The ambush site was on a dirt road between the villages of Los Pinos and Las Vigas.
Killing is a lark: for the gunmen as lolly gag on a rock before the deadly ambush on cops
Police say they have arrested one of the gunmen and that the video is serving as evidence against him.
Mexican authorities are now investigating how the video leaked online.
One of the hitmen has been arrested with the video used as evidence