Police in Newtown, Connecticut are responding to a report of shots fired at Sandy Hook Elementary School. According to the Hartford Courant, there are a number of injured parties at the scene.

Shortly after 9:40 a.m., police reported that a gunman was in the school's main office. A person in one room of the building was reported to have "multiple gunshot wounds."

Students, some crying, some holding hands, were escorted away from the school in groups by their teachers. As of 10:30 a.m., some students still remained in the school building.

UPDATE: The Courant reports that one person is dead. Sources say that the deceased person is the shooter. Parents of children at Sandy Hook Elementary can pick up their children at the fire station close by the school.

UPDATE (12:33 p.m.): The Courant reports that there have been multiple deaths, including children. The shooting began in a kindergarten classroom.

UPDATE (12:36 p.m.): WABC reports that more than 12 people are dead, according to a state official. Police are reporting that all children and the shooter have been cleared from the school, but police are still treating the incident as an active shooting.

UPDATE (12:45 p.m.): KCBS News reports that at least 27 people are dead, including 14 children.

UPDATE (12:55 p.m.): Hartford Courant is reporting that one whole classroom of children is unaccounted for.

UPDATE: 1:21 p.m. NBC News has reported that the shooter was a 20-year-old man believed to be living in Connecticut. The network also played an interview with an unidentified female child who attends the school.

"I was in the gym and I heard like seven loud booms and teachers told us to go in the corner," she said. "I kept hearing these booming noises. All the gym teachers told us to go into the office where no one could find us. A police officer came in and told us to run outside."

NBC is also reporting that a 2nd person is in custody in connection with the shooting.

UPDATE (1:48 p.m.): At a police press conference, Gov. Dan Malloy (D)'s spokesperson Roy Occhiogrosso and Connecticut State Police Lt. Paul Vance declined to give names of any of the dead or wounded, nor did they give an exact number of deceased, pending notification of the families. Lt. Vance said that the public is not in danger, that the shooter is dead, but he did not specify by what means.

UPDATE (1:57 p.m.): The current number of fatalities is 27, 18 of whom are children. Other schools in the area are currently on lock-down.

UPDATE (2:17 p.m.): The website CT Talking is reporting that a body has been found in a home connected to the 20-year-old man who allegedly carried out today's shooting.

NBC News reported at 2:10 p.m. that the body found in the home is one of the shooter's parents.

UPDATE (2:20 p.m.): CNN Headline News is reporting that the 20-year-old suspect's name is Ryan Lanza. CNN also reported that among the dead are the school's principal and school psychologist. [Please see the update at 4 pm for clarification.]

The Associated Press also identified the shooter as 20-year-old Ryan Lanza. [Please see the update at 4 pm for clarification.]

UPDATE (2:26 p.m.): NBC News is now reporting that Lanza is actually 24 years old and that his mother was a teacher at the school and is among the dead, contradicting earlier reports that a parent was found dead in Lanza's home and that he was 20 years old. [Please see the update at 4 pm for clarification.]

UPDATE (2:34 p.m.): NBC confirms that the classroom where Lanza opened fire was the one in which his mother was teaching.

UPDATE (2:46 p.m.): Lanza was dressed in black paramilitary gear when he carried out the shooting. He was armed with three guns, two handguns and a longer, assault-style weapon, according to NBC.

UPDATE (3:09 p.m.): President Barack Obama will address the nation at 3:15 p.m., according to NBC. NBC also reports that the other person taken into custody by police was Ryan Lanza's younger brother. Another Lanza family member whose relationship is currently not available to the public was found dead in a house in Newtown. [Please see the update at 4 pm for clarification.]

UPDATE (3:12 p.m.): Senate Majority Leader Sen. Harry Reid (D-NV) has issued a statement regarding the tragedy: "I am in shock and disbelief at this horrible tragedy that took so many innocent lives today. As a father and grandfather, it is beyond my comprehension why anyone would want to hurt innocent children. I join the millions of Americans whose thoughts and hearts are with those suffering because of this horrible crime in Connecticut.”

UPDATE (3:32 p.m.): President Obama addressed the nation just after 3 pm, tearing up as he spoke of the children who died today. Video of his speech can be seen here.

UPDATE (3:40 p.m.): Captain Mark Kelly, an astronaut and the husband of Tucson shooting victim former Rep. Gabby Giffords (D-AZ), said on his Facebook page:

I just woke up in my hotel room in Beijing, China to learn that another mass shooting has taken place - this time at the Sandy Hook Elementary School in CT. My thoughts and prayers are with the families of the victims and the entire community of Newtown, CT. I just spoke to Gabby, and she sends her prayers from Tucson.

As we mourn, we must sound a call for our leaders to stand up and do what is right. This time our response must consist of more than regret, sorrow, and condolence. The children of Sandy Hook Elementary School and all victims of gun violence deserve leaders who have the courage to participate in a meaningful discussion about our gun laws - and how they can be reformed and better enforced to prevent gun violence and death in America. This can no longer wait.

UPDATE (3:45 p.m.): State Police report that 20 children and 6 adults were killed by the shooter, who killed himself at the scene. There is an additional adult victim at a secondary scene.

UPDATE (4:00 p.m.): NBC reports that the shooter may have been carrying another man's ID, and the NY Post reports that the suspected shooter is actually Adam Lanza. Former Jersey Journal report Brett Wilshe told the paper that he spoke with the Ryan Lanza identified by news outlets including the Huffington Post and CNN as the Lanza involved in the shooting, and Ryan Lanza confirmed that he was not involved in the shooting and the shooter might have had his ID.

UPDATE (4:00 p.m.): A second official confirmed to the AP that Adam Lanza is the shooter, not the Ryan Lanza whom media outlets earlier identified as the shooter (but who is Adam Lanza's older brother).

UPDATE (6:00 p.m.): Sen. Charles E. Schumer (D-CT) released a statement regarding the tragic shooting:

The horror of what happened is beyond words and leaves a permanent lump in your throat. To senselessly lose so many innocent lives breaks your heart. Our thoughts and prayers go out to all who lost a loved one today, to all who are injured, and to those that survived. The people of New York will help in any way we can as our fellow citizens struggle to comprehend today’s events. Perhaps an awful tragedy like this will bring us together so we can do what it takes to prevent this horror from being repeated again.

UPDATE (6:30 p.m.): Multiple news outlets are reporting that the mother of the alleged shooter was not killed at the elementary school but may have been killed at her home. CBS News tweeted around 6:00 pm, "UPDATE: A source tells ‪@CBSNews‬ Connecticut school shooter Adam Lanza's mother has been found dead in her house." A federal law enforcement official told Fox News that Lanza's mother, Nancy, was killed at her home in Connecticut.

UPDATE (7:30 p.m.): NBC Nightly News reported that the guns involved in the shooting were registered to the suspect's mother. Sources also told Fox News that the guns were registered to the mother.

UPDATE (9:53 p.m.): Not much is known about the alleged shooter at this point. The Associated Press reported that the suspect's brother told law enforcement that his brother had a personality disorder and might be "somewhat autistic" (However, during a controversy over comments Joe Scarborough made regarding the Aurora shooting in Colorado and autism, an advocacy group released a statement claiming there is no link between autism and violence). ABC News reported that a relative told the news outlet that Adam Lanza was "obviously not well."

Watch video about this story, embedded below:

Visit msnbc.com for breaking news, world news, and news about the economy

Here is a live stream from the local NBC station:

View more videos at: http://nbcconnecticut.com.