WASHINGTON (AP) -- A law enforcement official says the suspect in the Connecticut school shootings is 20-year-old Adam Lanza, the son of a teacher at the school where the shootings occurred. A second law enforcement official says the boy's mother, Nancy Lanza, is presumed dead.
The first official says Adam Lanza's older brother, 24-year-old Ryan, of Hoboken, N.J., is being questioned by police. An earlier report from a law enforcement official mistakenly transposed the brothers' first names.
Both officials spoke on the condition of anonymity because they were not authorized to speak on the record about the developing criminal investigation.
The first official said Adam Lanza is dead from a self-inflicted gunshot wound.
By PETE YOST, Associated Press
(CNN) As many as 27 people died Friday in a school shooting in Newtown Connecticut, a law enforcement source with knowledge of the investigation told CNN.
At least 18 of the dead at Sandy Hook Elementary School were children.
A parent who was inside the school at the time of the attack said she heard what sounded like at least 100 rounds being fired. She said she saw two school employees who had died.
Hospital officials in neighboring Danbury said they were treating three people wounded in the shooting. Danbury Mayor Mark Boughton said the victims were in "very serious" condition.
The shooter is dead, a source with knowledge of the investigation told CNN's Susan Candiotti. The suspect's body is in a classroom at the school, the source told CNN.
Police have recovered two weapons from the suspect, a Glock and a Sig Sauer, the source said. It's unclear if police killed the suspect.
The Newtown Bee newspaper said one child had been carried out by a police officer and emergency crews had set up triage facilities, expecting additional patients. The Hartford Courant newspaper said one victim had "numerous gunshot wounds."
Aerial images from CNN affiliate News 12 New Jersey showed police officers armed with rifles following a dog into woods near the school.
Other officers, some in tactical gear, stood around the school with guns drawn, CNN affiliate WFSB reported.
A photograph published by The Newtown Bee showed teachers and police leading students out of the building across a parking lot.
One student, a third-grader, told CNN affiliate WTNH that she was sitting in her classroom when police flooded the area.
"We saw police officers and we heard them on our roof and in our building," the girl said.
Some of the children were crying, and others felt they had a stomachache, she said.
The girl's father told the station the incident was shocking.
"I was pretty shaken up," he said.
All schools in the city were on lockdown Friday as police assessed the situation, state police spokesman Lt. Paul Vance said.
Students were evacuated to a nearby firehouse, the Danbury News-Times newspaper reported.
The first calls came into police around 9:40 a.m., according to media accounts.
Police scheduled a news conference for 1 p.m. ET.
Newtown is about 60 miles north of New York.
CNN's Susan Candiotti and Meredith Artley contributed to this report.