GOLDEN – Authorities released nearly 1,000 pages of documents from the Columbine High School massacre Thursday, including step-by-step plans of the two killers as they gleefully plotted the slaughter that left 13 people dead.”Hell on Earth – ahh, my favorite,” Dylan Klebold writes in the 1998 yearbook of Eric Harris above a drawing of a gun-wielding headless soldier. “So many people need to die.”The documents released by the Jefferson County sheriff include essays, school work and computer files from Harris and Klebold, the two suicidal killers. It also includes a journal kept by Harris’ father that refers to disciplinary and psychological problems involving his son – but sheds no light on whether he knew the teen might be capable of the deadliest school attack in U.S. history.A scrawled entry in a Klebold day planner apparently sketches out April 20, 1999, down to the minute, starting with a 6 a.m. meeting, a 10:30 a.m. “set up,” an 11:12 a.m. “gear up” and at 11:16 a.m., “HAHAHA.””Have fun!” Klebold writes in another notebook.More than 20,000 documents and videos have been released since the attack and some of the details released Thursday have been disclosed. Some documents include blacked-out portions, including song lyrics, names and computer logons. Sheriff Ted Mink also refused to release videotapes made by the gunmen, concerned they would encourage copycat attacks.Still, the new material offers a chilling insight into the killers in the months before the attack. They had “to do” lists, with each purchase of a gasoline or a weapon marked off, and they had a hit list with at least 42 entries (all redacted).On a calendar entry for April 20, the time 11:10 is at the top – an approximate reference to the time the attack began. Elsewhere in the calendar are notations including “get nails” and “get propane, fill my clips” and “finish fuses.”Document excerptsThe following are excerpts from the 936 pages of Columbine-related documents released Thursday by Colorado authorities. Typos are included:• “Since my father was a United States Air Force pilot, we had to move often. It is always hard to leave close friends behind. … I have lost many great friends, and each and every time I lost one, I went through the worst days of my life.” – gunman Eric Harris, undated document recovered from family computer.• “im happy, i finally got the courage to tell my parents what i really think. i put it on paper so they wouldnt think i was ‘talking back’ or haveing (sic) a ‘bad attitude’ or something.” – Harris, in undated online chatroom exchange with unidentified person.• “There are a few loopholes in the new Brady bill. The biggest gaping hole is that the background checks are only required for licensed dealers, not private dealers.” – gunman Eric Harris, undated school essay.• “Thorough and logical. A few formatting problems, however. Nice job. 69/75.” – teacher comments on December 1997 essay by Harris titled “Guns in Schools” in which he writes at one point: “Students can be very resourceful, and can find ways to avoid the (metal) detectors.”• “I will sooner die than betray my own thoughts, but before I leave this worthless place, I will kill whoever I deam unfit for anything at all. especially life. … I don’t forget people who wronged me, like (name redacted) he will never get a chance to read this because he will be dead by me before this is discovered.” – Harris diary, April 21, 1998.Timeline of the Columbine attack• 11:10: First lunch period begins. After eating, Daniel Rohrbough leaves the cafeteria with Sean Graves and Lance Kirklin.• 11:14: Eric Harris and Dylan Klebold plant bombs in the school cafeteria. The primary device fails to explode.• 11:19: Shouting “Go! Go!” the gunmen start shooting from the top of the stairs leading into the west side of the school. First shots kill two students – Rachel Scott and Daniel Rohrbough – outside the school.• 11:22: Cafeteria videotape shows numerous students along the west windows looking out toward the stairs leading to the west entrance.• 11:23 a.m. The first 911 call is made from the school. • 11:24: Students begin to run out of the cafeteria. School resource officer Neal Gardner exchanges gunfire with Harris, who is standing on the sidewalk leading to the west doors of the school.• 11:26: First police car arrives. Teacher Dave Sanders is shot inside the school.• 11:27: A pipe bomb goes off in the cafeteria. The gunmen enter the library and begin killing students there.• 11:35: The gunmen fire the last shot that kills a victim.• 11:46: A bomb partially explodes in the cafeteria. A second bomb partially detonates a minute later. Denver police Sgt. Dan O’Shea asks dispatch what is happening at Columbine and says, “Show me en route, in civilian attire.”• Noon: Gunmen return to the library.• 12:06: Two makeshift SWAT teams enter the school. Three of the wounded – Graves, Anne Marie Hochhalter and Lance Kirklin – are taken to hospitals.• 12:08: Harris and Klebold kill themselves.• 1:09: SWAT team enters the cafeteria. Evacuation of students and faculty members trapped inside the school begins.• 4:30: SWAT teams declare school under control.