"OK, are you OK right now?" the dispatcher asked.
The woman answered: "For now, hopefully."
Another call came from a custodian, Rick Thorne, who said that a window at the front of the school was shattered and that he kept hearing shooting.
While on the line with Thorne, the dispatcher told somebody else: "Get everyone you can going down there."
Thorne remained on the phone for several minutes.
"There's still shooting going on! Please!" the custodian pleaded as six or seven shots could be heard in the background. "Still, it's still going on!"
Within 11 minutes of entering the school, Lanza had fatally shot 20 children and six educators with a semi-automatic rifle. Lanza also killed his mother in their Newtown home before driving to the school. He committed suicide as police closed in.
Newtown police officers arrived at the school within four minutes of the first 911 call, but nearly six more minutes passed before they entered the building while they sorted out concerns over a possible second shooter, according to a prosecutor's report issued last week.
It's not clear whether the delay made a difference because Lanza killed himself one minute after the first officer arrived on the scene, according to the report.
In one of the recordings released Wednesday, dispatchers were heard making three calls to Connecticut state police that apparently rang unanswered.
But state police had already been dispatched to the school by the time those calls were made, according to a timeline and call log supplied by Newtown officials.
In all, seven recordings of landline calls from inside the school to Newtown police were posted Wednesday. Calls that were routed to state police are the subject of a separate, pending freedom of information request by the AP.
"We all understand why some people have strong feelings about the release of these tapes. This was a horrible crime," said Kathleen Carroll, AP executive editor and senior vice president.