shot. cop shot. reporter: officer rivera, just 22-years-old, is killed. standing right behind him, his partner, 27-year-old wilbert mora. mora is then shot in the back of the head. a third officer, also a rookie, returned fire, hitting mcneil, who s now in the hospital. both officers rushed to the hospital just three blocks away. officer mora tonight fighting for his life. hours later, a silent procession for officer rivera. this was just not an attack on three brave officers. this was an attack on the city of new york. reporter: the nypd releasing this picture of the glock they say mcneil used to ambush the officers, blood on the floor, and a magazine capable of holding up to 40 rounds. authorities say the gun was reported stolen in 2017 and are trying to figure out how it wound up in mcneil s hands.