By Laila Kearney and Edward McAllister
NEW YORK (Reuters) - New York Mayor Bill de Blasio faced the biggest crisis of his time in office on Sunday following the fatal shooting of two police officers, in an attack intended as retribution for recent U.S. police killings of unarmed black men.
Police said the daylight Saturday shooting was the work of a 28-year-old black man who traveled from Baltimore that day after shooting and wounding his girlfriend, having warned on social media that he planned to be "putting wings on pigs," using an anti-police slur.
The gunman's posts on Instagram indicated he had been motivated by the deaths of 18-year-old Michael Brown and Eric Garner, a 43-year-old father of six, at the hands of police officers.
Grand juries reviewed both cases but found that the officers involved broke no laws, decisions that sparked weeks of sometimes violent protests across the United States, particularly in New York, the St. Louis suburb of Ferguson, Missouri, and Berkeley, California.
The decisions and subsequent protests prompted Barack Obama, the first black U.S. president, to set up a task force last week charged with rebuilding trust between police and minority communities.
Neither of the officers killed on Saturday, Rafael Ramos, 40, and Wenjian Liu, 32, were white. Ramos was Hispanic and Liu Asian-American.
The city's Roman Catholic cardinal, Timothy Dolan, warned of rising tensions during a service on Sunday attended by de Blasio and Police Commissioner William Bratton.
"We mourn the brutal and irrational execution of two young, promising, devoted police officers," Dolan said at St. Patrick's Cathedral. "We worry about a city tempted to tension and division."
De Blasio and Bratton, who described the attack as an assassination, left without speaking to reporters.
"There is an anger across this city that the people who are in charge are not talking," said political analyst Basil Smikle. "The conversation between Mayor de Blasio and the police seems to be shut off altogether."
The city's largest police union lashed out at de Blasio.
"There's blood on many hands," said Patrick Lynch, head of the Patrolmen's Benevolent Association. "That blood on the hands starts on the steps of City Hall in the office of the mayor."
The PBA had previously started a campaign in which officers could fill out a form asking the mayor and other officials not to attend their funerals if they were to die in the line of duty.
It was not clear on Sunday how many officers had filled out the forms and information was not yet available on funeral plans for the victims of the first fatal shootings of on-duty members of the largest U.S. police department since 2011.
Outside St. Patrick's, churchgoers reacted with exasperation and sadness.
"All of this senseless stuff has to stop," said Bernadette O'Connor, a 43-year-old school teacher from New York's suburbs after the service. "It has to come to an end."
Ramos' 13-year old son bid his father good-bye in a Facebook post late Saturday. "It's horrible that someone gets shot dead just for being a police officer."
LONG CRIMINAL RECORD
A clearer picture emerged on Sunday of the gunman, Ismaaiyl Abdula Brinsley, who Bratton said attacked the unsuspecting officers while they were sitting in their patrol car outside a Brooklyn housing project before running into a subway station where he shot and killed himself.
Court and jail records in Georgia, showed that Brinsley had a criminal record in that state dating back at least a decade.
Brinsley was booked into jail in Fulton County, Georgia, nine times between 2004 and 2010 on charges including simple battery, shoplifting, obstructing a law enforcement officer and terroristic threats, online records show.
During the day on Saturday, Brinsley cited the deaths of Garner and Brown in threatening posts on the Instagram social media service, in which he said "they take 1 of ours ... let's take 2 of theirs."
Baltimore police said they notified their New York counterparts of the threat after seeing digital evidence that the Brinsley had traveled to Brooklyn. Their alert came less than an hour before his attack.
Police on Sunday identified Brinsley's girlfriend, who he shot and wounded in Baltimore before heading to New York. She is Shaneka Nicole Thompson, 29, and was listed in critical but stable condition at an area hospital, police said.
Meanwhile, 30 miles northwest of Tampa, Florida, a police officer on duty was shot and killed early Sunday, local authorities reported. They had not yet released a motive for the attack.
Leaders of recent anti-police protests condemned the New York shooting.
"Any violence is an enemy to the pursuit of justice for Eric Garner and Michael Brown," Sharpton said at a Sunday press conference, flanked by Garner's mother, Gwenn Carr.
Missouri Governor Jay Nixon, whose state saw weeks of sometimes violent protests after Brown's killing, expressed his sympathies.
"Violence against police officers simply cannot be tolerated -- ever," Nixon said in a statement. "I stand with all Americans in condemning this unspeakable and cold-blooded act."
(Additional reporting by Ian Simpson in Washington, Anna Yukhananov in Baltimore and Colleen Jenkins in Winston-Salem, North Carolina; Writing by Scott Malone, editing by David Evans and Diane Craft)