NEW HAVEN, Conn. (AP) -- Connecticut police released thousands of pages Friday from their investigation into the Newtown massacre, providing the most detailed and disturbing picture yet of the rampage and Adam Lanza's fascination with murder, while also depicting school employees' brave and clearheaded attempts to protect the children.
Among the details: More than a dozen bodies, mostly children, were discovered packed "like sardines" in a bathroom where they had hidden. And the horrors encountered inside the school were so great that when police sent in paramedics, they tried to select ones capable of handling what they were about to witness.
"This will be the worst day of your life," police Sgt. William Cario warned one.
The documents' release marks the end of the investigation into the Dec. 14, 2012, shooting at Sandy Hook Elementary that left 20 first-graders and six educators dead.
Lanza, 20, went to the school after killing his mother, Nancy, inside their home. He committed suicide with a handgun as police arrived at the school.
Last month, prosecutors issued a summary of the investigation that portrayed Lanza as obsessed with mass murders and afflicted with mental problems. But the summary said his motive for the massacre was a mystery and might never be known.
In releasing the huge investigative file Friday, authorities heavily blacked out the paperwork, photos and videos to protect the names of children and withhold some of the more grisly details. But the horror comes through at nearly every turn.
Included were photographs of the Lanza home showing numerous rounds of ammunition, gun magazines, shot-up paper targets, gun cases, shooting earplugs and a gun safe with a rifle in it. The documents also indicated Lanza was interested in mass killings, played violent video games and had books that dealt with death.
A former teacher of Lanza's was quoted as telling investigators that Lanza exhibited anti-social behavior, rarely interacted with other students and wrote obsessively "about battles, destruction and war."
"In all my years of experience, I have known (redacted) grade boys to talk about things like this, but Adam's level of violence was disturbing," the teacher told investigators. The teacher added: "Adam's creative writing was so graphic that it could not be shared."
The documents also fill in more details about how the shooting unfolded and how staff members looked out for the youngsters.
Teachers heard janitor Rick Thorne try to get Lanza to leave the school. One teacher, who was hiding in a closet in the math lab, heard Thorne yell, "Put the gun down!" An aide said that she heard gunfire and that Thorne told her to close her door. Thorne survived.
Teacher Kaitlin Roig told police she heard "rapid-fire shooting" near her classroom. She rushed her students into the classroom's bathroom, pulled a rolling storage unit in front of the bathroom door as a barricade and then locked the door.
She heard a voice say, "Oh, please, no. Please, no." Eventually, police officers slid their badges under the bathroom door. Roig refused to come out and told them that if they were truly police, they should be able to get the key to the door -- which they did.
Others weren't so lucky.
Police Lt. Christopher Vanghele said he and another officer found what appeared to be about 15 bodies packed in another bathroom. So many people had tried to cram inside the bathroom that the door couldn't be closed, and the shooter gunned them all down, Vanghele surmised.
Vanghele also recalled another officer carrying a little girl in his arms and running for the exit. Vanghele ran with him through the parking lot as the officer repeated, "Come on sweetie, come on sweetie." The girl didn't survive.
In a letter accompanying the files, Reuben F. Bradford, commissioner of the state Department of Emergency Services and Public Protection, wrote that much of the report was disturbing. But he added: "In the midst of the darkness of that day, we also saw remarkable heroism and glimpses of grace."
Lanza was diagnosed in 2006 with "profound autism spectrum disorder, with rigidity, isolation and a lack of comprehension of ordinary social interaction and communications," while also displaying symptoms of obsessive-compulsive disorder, according to Dr. Robert A. King, a professor at the Yale School of Medicine Child Study Center.
But he also told investigators that he observed nothing in Lanza's behavior that would have predicted he would become a mass killer. Contacted by The Associated Press, King referred questions to the Yale University press office.