The fatal shooting of New York City police officer Wenjian Liu was the second crime in a week involving a Chinese-American police officer in the city.

Liu, 32, and his partner Rafael Ramos, 40, were fatally shot multiple times while sitting in their car on duty in the Bedford-Stuyvesant section of Brooklyn on Dec 20.

Sergeant James Ng, president of the NYPD Asian Jade Society, a network for Asian police, said the officers were doing their jobs and "died as heroes".

Liu, a Brooklyn resident, had been on the NYPD for seven years and was married two months ago. Ramos was a two-year veteran and left behind two sons.

Sophia He, a Brooklyn bodega owner, told The Wall Street Journal that Liu frequently came in to buy scratch-off lottery tickets.

"Every time he was in here he was so happy," He told the Journal.

"Yesterday's assassination of two NYPD officers was a terrible tragedy," said New York City Councilman Peter Koo, who represents Flushing, Queens. "These brave souls were murdered simply because they wore a blue uniform. There is no room in a civil society for heinous acts such as this. My prayers are with their families during their time of mourning."

The officers' killer, Ismaayil Brinsley, 28, later shot and killed himself on a G train subway platform. Earlier in the day, Brinsley, who had a long arrest record, was suspected of shooting his girlfriend, Shaneka Thompson, 29, in Baltimore, Thompson, an insurance specialist for the Veterans Affairs Department, is expected to recover, the Daily Mail of London reported.

A candlelight vigil was held on Sunday near the scene of the shootings, where Brooklyn Borough President Eric Adams called for a halt to police reform protests.

"We are asking all New Yorkers to turn this pain into purpose to ensure we send out a very clear and loud message: All lives matter," said Adams, a former NYPD officer.

President Barack Obama said in a statement Saturday: "I unconditionally condemn today's murder of two police officers in New York City. 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.

"Tonight, I ask people to reject violence and words that harm, and turn to words that heal -- prayer, patient dialogue, and sympathy for the friends and family of the fallen."

The New York Post reported Sunday that two Con Edison workers had confronted Brinsley after witnessing the shooting of the officers, and followed him in their truck. He pointed his firearm at them before heading down into the subway. The workers' identification helped make police aware of Brinsley's whereabouts, the Post reported.

Brinsley, who the NYPD said was born in Brooklyn, had issued an ominous post on Instagram that he was going to kill two police officers in response to the deaths in the summer of Michael Brown in Missouri and Eric Garner on Staten Island, in altercations with police officers.

Grand juries decided not to indict the officers involved in both cases, Darren Wilson in Ferguson, Missouri, and Daniel Pantaleo in New York.

Brinsley had posted earlier Saturday on Instagram: "I'm putting wings on pigs today. They take 1 of ours, let's take 2 of theirs." He used the hashtags Shootthepolice RIPErivGardner (sic) RIPMikeBrown.

The no bills by the grand juries resulted in days of rioting, fires and looting in Missouri, and days of intermittent protests in New York, including an incident on the Brooklyn Bridge involving another Chinese-American officer.

Lieutenant Philip Chan suffered a broken nose on the Brooklyn Bridge on Dec 13, when he and his partner Lieutenant Patrick Sullivan attempted to arrest Eric Linsker, a City University of New York adjunct professor, who was filmed trying to throw a garbage can down on police on a lower level of the bridge. Four suspects face charges in the case, and two more are being sought.

Mayor Bill de Blasio and NYPD Commissioner William Bratton attended Mass at St. Patrick's Cathedral on Sunday, where Cardinal Timothy Dolan called for calm. He asked the police commissioner to tell his troops that "we love them very much, we mourn with them, we need them, we respect them, we're proud of them and we thank them".

The mother of Garner said: "I'm standing here in sorrow about losing those two police officers; that was definitely not our agenda. We are going in peace. and anyone who's standing with us, we want you to not use Eric Garner's name for violence because we are not about that. These two police officers lost their lives senselessly and our condolences to the family, and we stand with the families."

De Blasio has faced sharp criticism from some NYPD members, some of whom turned his back on the mayor as he arrived for a news conference Saturday to comment on the fatal shootings.

The Patrolmen's Benevolent Association (PBA) of New York recently issued a flier asking De Blasio and City Council Speaker Melissa Mark-Viveritonot to attend any funerals of fallen NYPD members. The form, titled "Don't Insult My Sacrifice", is on the PBA website.

Former New York Mayor Rudy Giuliani lashed out at de Blasio, Obama and Attorney General Eric Holder.

"We've had four months of propaganda starting with the president that everybody should hate the police," Giuliani said.

"They have created an atmosphere of severe, strong, anti-police hatred in certain communities, and for that, they should be ashamed of themselves," he said.

In a tweet, former New York Gov. George Pataki called the killings the "predictable outcome of divisive, anti-cop rhetoric of Attorney General Eric Holder and Bill de Blasio."

The NYPD has about 35,000 police officers, of whom 3,000 to 4,000 are Asian Americans and around 1,500 of those are of Chinese descent, Sergeant Ng told China Daily in a July interview with several Asian-American police officers.

Ng works out of the Midtown South precinct, which covers Times Square, Penn Station and the Garment District. He has been on the NYPD for more than 16 years; one of his brothers is also a sergeant on the force. Midtown South has 12 Chinese-American officers out of 350.

"Most Chinese-American officers on the NYPD are enterprising," said Officer Binhao Huang, who works in Flushing, a diverse community with a large Asian population.

"At least 40 percent of Chinese officers are supervisors," said Ng.

Although he never worked in a Chinese community before, Ng gets to interact with tourists from China because of his patrol near Times Square.

"People feel more comfortable when you can talk in their dialects," he said.

Lu Huquian and Amy He in New York and the AP contributed to this story.