(CNN) — Not too long after a man ambushed and killed two police officers sitting in a patrol car in New York City , the finger-pointing started.
Ismaaiyl Brinsley walked up to officers Wenjian Liu and Rafael Ramos on Saturday in Brooklyn, and shot both in the head, authorities said.
Police said he later used the same gun to commit suicide.
Former New York Gov. George Pataki and police union officials quickly lashed out at Mayor Bill de Blasio, whom they accused of putting officers’ lives at risk with his support for recent protests.
Police officers gathered at the hospital where the slain officers were taken followed suit. When the mayor entered a news conference to condemn the killings, they turned their backs on him.
As de Blasio walked by, officers quietly faced the walls.
Earlier, grieving officers and New York Fire Department personnel saluted an ambulance carrying the two officers as it made its way down the street.
They stood at attention, some with tears rolling down their cheeks.
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Ex-governor blames mayor
Pataki cast disdain at the mayor and the attorney general in a post on Twitter.
“Sickened by these barbaric acts, which sadly are a predictable outcome of divisive anti-cop rhetoric of Eric Holder and Mayor de Blasio,” he tweeted.
He was referring to de Blasio’s and Holder’s support for peaceful protesters decrying alleged police brutality after the killing of Eric Garner and Michael Brown, two unarmed black men who died in confrontations with officers this year.
Protesters have taken to streets nationwide to demand an end to killings of unarmed people by police officers.
Hours before Saturday’s attack, Brinsley appeared to make statements on social media implying he planned to kill officers and expressing outrage over the deaths of Garner and Brown.
Pat Lynch, the head of New York’s Patrolmen’s Benevolent Association, has vehemently attacked the mayor before and did so again the day of the shooting.
“There’s blood on many hands tonight,” Lynch said before making reference to the mayor’s office.
De Blasio did not respond to the denunciations against him, but he condemned the killing of the officers as an “assassination” while Holder described it as a “cowardly attack.”
#BlueLivesMatter and #BlackLivesMatter
Not to be outdone, social media users joined the fray. Others objected to the finger pointing.
Some turned to hashtags #BlackLivesMatter for Garner and Brown — and #BlueLivesMatter for police officers — to share their opinions.
“Everyone who turned Michael Brown into a saint, the assassination of those cops is on you,” username @mattcale52 tweeted.
Akilah Hughes said the trading of accusations is unnecessary.
“#BlackLivesMatter is a call for justice, not a call for retribution,” she tweeted. “Do not pin the death of these two NYPD officers on a peaceful movement.”
David Simpson said supporters should not pick one side or the other.
“… #BlackLivesMatter and #BlueLivesMatter and #AllLivesMatter,” he tweeted. “Recognize racism, push for justice for all.”
Officials weigh in
The murders triggered reactions of condemnation and sadness from across the nation. Here are a few:
President Barack Obama
“Two brave men won’t be going home to their loved ones tonight, and for that, there is no justification. The officers who serve and protect our communities risk their own safety for ours every single day — and they deserve our respect and gratitude every single day.”
New York City Mayor Bill de Blasio
De Blasio also called the shootings an “assassination.”
“It is an attack on all of us,” he said. “It is an attack on everything we hold dear.”
Eric Holder
“This cowardly attack underscores the dangers that are routinely faced by those who protect and serve their fellow citizens.
“Our nation must always honor the valor — and the sacrifices — of all law enforcement officers with a steadfast commitment to keeping them safe.”
Loretta E. Lynch
Obama’s nominee for attorney general is the current U.S. attorney for the eastern district of New York. She pledged her district’s support in the investigation.
“Today, two have fallen, in a stark reminder of the challenges and risks that our law enforcement officers face every day, both in New York City and throughout our nation,” Lynch said.
Michael Brown’s family
Brown’s family condemned the slayings.
“We reject any kind of violence directed toward members of law enforcement. It cannot be tolerated. We must work together to bring peace to our communities,” they said in a statement.
The Rev. Al Sharpton
“Any use of the names of Eric Garner and Michael Brown, in connection with any violence or killing of police, is reprehensible and against the pursuit of justice in both cases. We have stressed at every rally and march that anyone engaged in any violence is an enemy to the pursuit of justice for Eric Garner and Michael Brown.”