Adam Lanza, the Sandy Hooks Elementary School shooter, had enough ammunition to kill every student in the school if given enough time, The Associated Press reported Sunday.

He shot himself in the head as he heard police approached the classroom he was in about 10 minutes into the attack. But authorities found more ammunition in Lanza's possession in the form of multiple, "high-capacity" clips, each capable of carrying 30 bullets.

"There was a lot of ammo, a lot of clips," said state police Lt. Paul Vance. "Certainly a lot of lives were potentially saved."

Sandy Hook Elementary School has close to 700 students, Fox News reported.

Adam broke into the building on Friday, Dec. 14, carrying three weapons all legally registered to his mother, who enjoyed target shooting as a hobby. The 20-year-old killed 26 children and teachers Friday, but total death count that day was 28 considering his own suicide and the murder of his mother, Nancy, earlier that morning. He shot Nancy four times in the head, his first victim of the day, before making his way to the elementary school.

"Our hearts are broken today," Obama said in a brief address to the nation on Friday. "We've endured too many of these tragedies in these past few years, and each time I receive the news I react not as a president, but as a parent."

"Most victims were children, between five and 10 years old...They had their entire lives ahead of them, birthdays, graduations weddings, kids of their own."

All Newtown public schools except Sandy Hook School will re-open on Tuesday, Dec. 18, according to the school's website.

Nancy's friends said Adam suffered from Asperger's Syndrome, however, no direct link has been made between the condition, which is a form of autism, and Friday's mass shooting. The school incident is reportedly the second-deadliest school shooting, following 2007's Virgina Tech massacre where 33 people died.