A teacher’s son — clad in black and carrying two 9mm pistols — rampaged through a Connecticut elementary school Friday, killing 20 small children and six adults, including his mother, in the nation’s second-worst school shooting, law enforcement officials said.

The gunman, identified as Adam Lanza, 20, was also found dead at Sandy Hook Elementary School in Newtown, law enforcement officials said. Later, an unidentified woman was found fatally shot in the face at a home in Newtown after police showed up with there a bomb squad,  officials said.

Officials had initially misidentified the shooter to NBC News as Lanza’s brother, Ryan. But a senior official later said that Ryan was nowhere near the shooting, is not believed to be involved, and is cooperating with the investigation. Ryan told police that Adam has a history of mental illness, according to the senior official.

Their mother is a kindergarten teacher at the hilltop school, and most of the dead were found inside her classroom, according to NBCNewYork.com.

Some young survivors — ages 5 to 10 — described the terror of the shooting and a massive police response that included SWAT officers going room to room to search for victims as students huddled in classroom corners.

Robert Licata said his 6-year-old son was in class when the gunman burst in and shot the teacher.

“That’s when my son grabbed a bunch of his friends and ran out the door,” he told the Associated Press. “He was very brave.”

Click here to read more.