Moore was in a coma after undergoing brain surgery following the Saturday evening shooting.
The usually bustling back entrance of Jamaica Hospital fell into stunned silence Monday, with tears flowing under a cloudless sky as an NYPD ambulance carried away Moore's body as saluting officers, including his parents, lined the path.
At the 105th precinct Monday night, children came with their parents to try to share the heavy burden of grief with the officers there.
Firemen came to honor Brian Moore and neighbors left flowers, and they lit candles and they wondered, as bunting was raised again in the city, as flags were lowered again in the city, have we forgotten how important they are?
"Who marches for the cops now? Nobody does," a resident said.
The 25-year-old officer, on the job just five years but with more than 150 arrests under his belt, was shot Saturday as he and his partner pulled up to question 35-year-old Demetrius Blackwell, a career criminal police say had been adjusting his waistband as if he had a gun.
Authorities say he fired three times, hitting Moore in the face. On Monday, police say they recovered the weapon allegedly used in what prosecutors call an assassination.
Moore, who followed in the footsteps of his father, his uncle and his cousins, joined the department right out of high school in Massapequa five years ago.
In announcing his death, NYPD Commissioner William Bratton described Moore as an extraordinary man and said his passing is a great loss to the city.
"He proved himself to be an exceptional young officer," Commissioner Bratton said, noting Moore had earned meritorious service medals.
"As a member of the NYPD, Officer Moore put the safety of his fellow New Yorkers before his own, and we will remember his service with gratitude and pride," Gov. Andrew Cuomo said in a statement. "I join with all New Yorkers in mourning his passing and send my deepest condolences to his friends and family."
Charges against Blackwell were upgraded to murder after Moore's passing.
"I am deeply saddened by the passing today of New York City Police Officer Brian Moore, who lost his life in the line of duty while protecting and serving our community," Queens District Attorney Richard Brown said in a statement. "Our thoughts and prayers go out to Officer Moore's family and his fellow officers. Officer Moore's death is a stark reminder of the dangers that our police officers face each day and the risks that they take as they carry out their sworn duty to keep our streets safe."
The first-degree murder charge carries a penalty of life in prison without the possibility of parole.
President Barack Obama also responded to the news.
"As many of you know, New York lost one of its finest today in Officer Brian Moore, shot in the line of duty Saturday night," he said. "He passed away earlier today. He came from a family of police officers. And the family of officers, he joined in the NYPD, and across the country deserve our gratitude and our prayers, not just today but every day. They've got a tough job."
Blackwell, who officials say boasted of being a street "hellraiser" and who served prison time for attempted murder, was arraigned and ordered held without bail Sunday after appearing in Queens Criminal Court in a torn white jumpsuit. His hands were cuffed behind his back and legs shackled.
"New York City has lost another brave police officer who placed his life between crime and the good people of the city," PBA President Pat Lynch said. "Brian Moore is a hero in every sense of the word. His loss is felt by all of his brother and sister officers as we pray for Brian and for the loving family that he left behind. His family now becomes our family and we will support them in every way possible through the next difficult days and beyond. I'd like to express the gratitude of all New York City police officers for the support and prayers that have been shown by so many caring New Yorkers. God bless Brian Moore, his family and friends."
Police say Officer Moore and his partner, Officer Erik Jansen, 30, exchanged words with Blackwell before he turned suddenly and opened fired. Officer Jansen then radioed for help.
"The man immediately removed the firearm from his waistband and turned in the direction of the officers and deliberately fired several times at the vehicle, striking Officer Moore in the head," Bratton said at a press conference at a Queens hospital.
The shooting took place Saturday around 6:30 p.m. near 212th Street in Queens Village.
"They did not have an opportunity to get out and return fire," the commissioner said at a Saturday night news conference at Jamaica Hospital Medical Center with Mayor Bill de Blasio and other officials.
One woman who did not want to give her name lives in a house in Queens Village that was surrounded by police on Saturday night. The officers were looking for the weapon that Blackwell allegedly used to shoot officer Moore in the head. Police did locate it with two empty chambers, that housed, police believe, the bullets that killed a hero.
Authorities say the plainclothes officers, while riding in their unmarked car, spotted Blackwell, and saw him carrying what they believed was a gun. The officers asked him what he was carrying, and without warning, he allegedly pulled out a gun, and fired. One bullet struck Moore in the face.
The woman watched fellow officers place Moore in another patrol car and rush the officer to the hospital. She says she was standing on her front steps when Blackwell calmly walked up.
"We weren't talking about anything in particular," she said. "We weren't talking about what was going on with this - he was acting totally normal."
By then, teams of officers were looking for the gunman. She says police told her and Blackwell to go inside for safety reasons, and they did. Moments later, everything changed.
"The first SWAT went to this house, and then we saw them coming for ours, guns drawn, they said to open the door," she said.
The woman says officers took Blackwell away in handcuffs.
The married father of three has a lengthy criminal record and just served seven years in prison for attempted murder. He also has arrests for, among other things, robbery and assault.
The New York Police and Fire Widows and Children's Benefit Fund will be making a $25,000 distribution to Officer Moore's family. The Benefit Fund is an independent, non-profit organization that provides financial assistance and a network of support for the families of New York City first responders who are killed in the line of duty.
"It is a painful day for all of us," de Blasio said. "It is a reminder of the dangers that all of our officers face every single day."
Monday night, more than 1,000 people gathered at the Plainedge High School football field Monday night to remember, mourn, and honor Officer Moore.
Retired New York City Firefighter Eric Szillus organized this event. He wanted to turn his anger over the shooting into something positive, into support for the Moore family.
County leaders and relatives attended.
Officer Moore graduated from Plainedge High School in 2007 and keeping with tradition became a proud member of the NYPD.
"We need to be thankful that there was a hero amongst us named Brian Moore," Mayor de Blasio said.
The family says they expect his funeral to take place on Friday.