New York is reeling after the murder of two uniformed cops by a man who told bystanders to "watch what I'm going to do" just before the killings.
Candles, flowers and an American flag were placed at a makeshift memorial at the scene of the shooting, which apparently was out of revenge for the recent killings of unarmed black men by police.
A sombre mass was held at Saint Patrick's Cathedral in Manhattan and the New York Jets football team held a moment of silence. After nightfall, supporters gathered for a candlelight vigil, singing and saying prayers.
The two officers - Wenjian Liu, 32, and Rafael Ramos, 40 - were shot in the head through the window of their patrol car on Saturday in Brooklyn in an attack that has shocked America's biggest city just days before Christmas.
Police named the shooter as Ismaaiyl Brinsley, 28. He fled to a nearby subway station after the attack, where he shot himself in the head on the platform.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Investigators said Brinsley had shot his ex-girlfriend, who survived, at her apartment outside Baltimore before heading for New York.
Just before the shooting, Brinsley spoke with bystanders, asking them about their gang affiliation, urging them to follow him on Instagram and to "watch what I'm going to do", the New York Police Department's chief of detectives Robert Boyce said.
"They Take 1 of Ours... Let's Take 2 of Theirs," read a comment seemingly written by Brinsley on Instagram just hours before the assault, next to a photo of a silver handgun.
Brinsley had been arrested at least 19 times, Boyce said, mostly while living in Georgia, on charges ranging from disorderly conduct to terror threats.
The double killing, in a city where murders are at their lowest rates in 20 years, further strained the already fraught relations between Mayor Bill de Blasio and police.
A number of officers, in apparent homage to their slain colleagues, turned their backs to the mayor at the hospital where the two cops were pronounced dead.
Police officers accuse de Blasio of failing to support them and of being too sympathetic to demonstrators who, in recent weeks, have been protesting police violence against African Americans.
De Blasio responded to criticism - including from former state governor George Pataki - by calling for an end to "irresponsible, overheated rhetoric that angers and divides people."
Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Suicide Call Back Service 1300 659 467
