US authorities on Wednesday released audio recordings of emergency calls made to police from the elementary school in Newtown where a lone gunman shot dead 20 children and six adults last year. Recordings of a series of 911 calls made from within and nearby the school were released nearly a year after the tragedy at Sandy Hook Elementary School on December 14, 2012. Adam Lanza, 20, murdered 20 children and six adults in less than 11 minutes in one of the deadliest U.S. school shootings. The recordings detail a calm response from emergency service personnel as gunshots ring out in the background at the school in the state of Connecticut. "Sandy Hook school, I think there's somebody shooting in here, Sandy Hook school," said one audibly upset woman. "There's still shooting. Sandy Hook school please." A call from a man "down the corridor" said that the front glass had been "all shot out." Over bursts of gunfire he said: "It's still happening." Emergency personnel are also heard telling a third woman to keep everyone down, away from the windows. The Associated Press news agency took legal action to get the calls released after officials initially argued they should be withheld on the grounds that they relate to child abuse. The Freedom of Information Commission ruled that the recordings should be made public under the Freedom of Information Act. The calls were made available a week after the official investigation was unable to find a motive for the massacre other than conclude that the killer was obsessed with mass murders and firearms. Lanza first killed his mother, shooting her multiple times in the head as she lay in bed, and then shot his way into the school he once attended. He killed the principal and school psychologist in the hallway, then entered two first-grade classrooms, killing two adults in each room, 15 children in classroom eight and five in classroom 10. Police arrived less than four minutes after receiving an emergency call. But Lanza killed himself a minute later with a single shot with a pistol.