DEVELOPING: Thirteen people are dead after a gunman opened fire at an immigration center in Binghamton, N.Y.
The shooter was identified as a local resident of Asian descent named Jiverly Voong. There were conflicting reports as to whether he was 41 or 42. Local authorities told The Associated Press he died of a self-inflicted gunshot wound.
Voong blocked the back door of the building with his car, then stormed in through the front entrance while firing a high-powered gun. Several people were taken hostage.
The bloodbath killed 12 people plus the gunman, who also goes by the name of Linh Phat Voong and lived in the Binghamton suburb of Johnson City.
Voong wore a bright green nylon jacket and dark-rimmed glasses as he executed victim after victim, according to local media. His body was found on first floor with a hunting knife jammed into the waistband of his pants, the reports said.
A federal law enforcement official told the AP that the gunman's body was discovered inside the upstate civic center.
Click here for photos.
New York Gov. David Paterson confirmed the deaths and expressed his condolences to the victims' families.
"This is a tragic day for New York," Paterson said in a prepared statement. "While the situation is still developing and details are being gathered, we do know that a gunman entered the American Civic Association in Binghamton this morning and that there are fatalities."
Local cops were mum on the number of casualties in the rampage.
Binghamton Police told FOXNews.com that they couldn't give the precise number shot because it was still "an active scene."
The Associated Press reported that at least 41 people were taken hostage, citing police and media sources.
The gunman barricaded the rear door of the civic center with his car before entering through the front door, firing his weapon, at about 10:30 a.m. EDT Friday, a law enforcement official told the AP.
SWAT team officers have surrounded the building but "they do not have it secured," a Binghamton police spokesman told FOXNews.com.
Later, the spokesman said it would be "hours" before the situation was under control at the immigration center.
Binghamton Mayor Matthew Ryan told the Press & Sun Bulletin newspaper that the gunman had a high-powered rifle.
Paterson expressed "prayers for the victims and families" and said his staff is monitoring the situation. He has instructed state police to help Binghamton authorities "in any way they can."
Emergency dispatchers were in contact with some people inside by phone, WBNG-TV reported. The gunman might still be in the building, the station reported.
Police have locked down a nearby high school and advised local business owners to stay inside.
People escaped to the basement of the building and more than a dozen people hid in a closet, WBNG reported.
The FBI sent hostage negotiators and an evidence response team to the scene, said a law enforcement official who was not authorized to speak about details of an ongoing hostage response and spoke on condition of anonymity.
Earlier, a local hospital said they were treating at least five shooting victims.
The five with gunshot wounds were at the Wilson Medical Center, one in critical condition, hospital spokeswoman Christina Boyd told FOX News.
The wounded ranged in age from 20 to their mid-50s, and their conditions ranged from stable to critical, she said.
Hospital staff were in the process of notifying the families, according to Boyd. None of the victims were immediately identified, and there were extra doctors and nurses there to handle the emergency, she said.
Apartments and schools in the area were evacuated or placed on lockdown.
There were classes scheduled Friday at the immigration services center, located in the same town as Binghamton University, part of the State University of New York (SUNY).
Linda Miller, a spokeswoman at Our Lady of Lourdes Hospital in Binghamton, confirmed that a student from Binghamton University was being treated at the emergency room. Miller said she didn't know the nature of the injuries.
"We're on full alert anticipating we're going to get additional casualties," Miller said.
Around 1 p.m., Pennie Kerber, 72, told the AP in a phone call from her home across the street that the scene appeared to be settling down.
"The cops are all standing around in the front now. They're still all over the roof for sure," she said. "The SWAT shooters that were to the side of the building look like they're not there any more. It looks like it's clearing."
The area is in a stretch on the west side of the Chenango River in the city of about 45,000 near the Pennsylvania border. Emergency vehicles lined the streets in the neighborhood, a mix of homes and small businesses.
College student Leslie Shrager told the AP that she and her five housemates were sleeping when police pounded on the front door of their house next door to the shooting scene.
Officers escorted the six Binghamton University students outside, she said, and that's when they learned of the shooting.
"One of our housemates thought they heard banging of some kind. But when you're living in downtown Binghamton, it's always noisy," said Shrager, of Slingerlands, an Albany suburb. "Literally two minutes later the cops came and got us out."
The American Civic Association describes itself as helping immigrants and refugees with counseling, resettlement, citizenship, family reunification and translators.
It also intervenes with emergencies, including fighting, hunger and homelessness, according to information from the association's Web site.
U.S. senators Charles Schumer and Kirsten Gillibrand of New York said in a joint statement that "our hearts and prayers go out to the victims and their families. We are monitoring the situation closely and will do everything we can to help."
FOXNews.com's Catherine Donaldson-Evans and The Associated Press contributed to this report.
This is a developing story. Please refresh page for updates.