Twenty-seven people, including 20 children, are dead after a shooting Friday at an elementary school in Newtown, Connecticut, in an attack that Mayor Michael Bloomberg says is "almost impossible to believe."
The shooting occurred inside Sandy Hook Elementary School in Fairfield County, about 60 miles north of New York City.
The Hartford Courant reports many of the shootings took place inside a kindergarten classroom.
Bloomberg, who has been an outspoken advocate of gun control, says now is the time to start a serious conversation about gun laws.
He released a statement that said, in part:
"For every day we wait, 34 more people are murdered with guns. Today, many of them were five-year olds. President Obama rightly sent his heartfelt condolences to the families in Newtown. But the country needs him to send a bill to Congress to fix this problem. Calling for 'meaningful action' is not enough. We need immediate action. We have heard all the rhetoric before. What we have not seen is leadership - not from the White House and not from Congress. That must end today. This is a national tragedy and it demands a national response."
The Associated Press says law enforcement officials have identified the suspect in the shooting as Adam Lanza, 20, who was found dead on the scene.
A law enforcement official told the Associated Press that some of the guns used by Lanza are the same model as guns owned by his mother, but the official said it's not certain they were the same guns.
Police said Lanza killed his mother in her home, then drove to Sandy Hook Elementary in Newtown.
At around 9:30 a.m., police say he opened fire, killing 20 children, six adults and then himself.
The children killed ranged from 5 to 10 years old.
"There were three children that came out," said one witness at the scene. "One of them had a very bloody face. It was a very violent scene and there were two other ones that they were, you know, in the arms of a state trooper. They did not move. Their faces were very pale."
"Evil visited this community today, and it's too early to speak of recovery," said Connecticut Governor Dannel Malloy.
President Barack Obama said he will provide every resource he can to investigate the shooting.
"Our hearts are broken today for the parents and the grandparents, sisters and brothers of these little children, and for the families of the adults who were lost," Obama said.
The National Rifle Association declined to comment on the shooting "until the facts are thoroughly known."
Authorities say the names of those killed will likely be released Saturday.
Adam Lanza's brother, Ryan, lives in Hoboken and is reportedly cooperating with investigators. He is not thought to be connected to the attack.
Authorities questioned him following the attack, and New Jersey police and the FBI gathered information from inside his apartment.
Local residents said they were shocked to see the police presence in their neighborhood.
"It's very weird walking home and seeing all this and then, you know, seeing seven or eight cops in your building," said one resident. "Usually, yeah, it's a great place to live, and seeing this its awful."
"I'm a teacher in Hoboken," said another. "I'm a pre-K special ed teacher and, you know, it hit home because I'm a teacher."
Sources also told the AP that Ryan told police he and his brother haven't spoken in years.
Hundreds of Newtown residents packed Saint Rose of Lima Church for a vigil for the victims Friday night.
Some parents say they're dealing with mixed emotions knowing their children survived while others did not.
Malloy encouraged the community to come together in the midst of the tragedy.
"In the coming days and in the coming weeks, I will pray that you will embrace one another, that you lift one another up, that you understand the difficulties that you collectively, will undergo," Malloy said. "Keep in your prayers the children who lost their lives today. Keep in your prayers the adults who lost their lives today."
A letter from Pope Benedict XVI was also read. The pope said his prayers go out to all those who are mourning.