The first detail, reported as early as 3pm on the 14th in a NY Daily News article, is that the weapons used were a Bushmaster .223 caliber assault rifle, a Sig-Sauer 9mm, and a glock 9mm.
The second detail appears in the same article:
“The two pistols were found inside the school and a .223-caliber Bushmaster rifle was found in the back of his mother’s car in the parking lot.”
The third detail, reported as early as 8pm on the 15th in a NY Post article, is that the children were shot with a rifle, an observation made by Connecticut Chief Medical Examiner H. Wayne Carver II (that this detail originated from Carver is confirmed by the video in the ABC Malloy link below):
“Chief Medical Examiner H. Wayne Carver II said all of the children killed in yesterday’s massacre were shot more than once, and most were first-graders. Two of the seven children he examined were shot at close range. All of the children were shot with a ‘long rifle,’ that was one of three weapons madman Adam Lanza, 20, was armed with when he drove to Sandy Hook Elementary School and carried out his killing spree yesterday.”
This detail is indirectly corroborated by the report that .223 rifle shell casings were found:
The third detail is also reported in an article by Huffington Post:
“Lanza blasted his way into the building and used a high-power rifle to kill 20 children and six adults, including the principal who tried to stop him, authorities said.”
Finally, the fourth detail originates from Governor of Connecticut Dan Malloy speaking on ABC’s This Week:
“Gov. Dannel Malloy said Lanza shot himself as police entered the building. ‘We surmise that it was during the second classroom episode that he heard responders coming and apparently at that, decided to take his own life,’ Malloy said.”
Malloy strongly implies that Adam took his own life while inside the school, mid-”episode.” If this is the case, it seems strange that the rifle would be in the backseat of the car when first responders arrived, as per the second detail. If Adam had been in the middle of shooting kids when he decided to kill himself, he would have been in the middle of using the rifle, which means the only way to reconcile the details is to assume he realized cops were on the way, went back out to his car and put the rifle in the backseat, then went back inside the school, and shot himself.
Most likely there was at least one other rifle involved. Adam could not have used his mother’s rifle to kill anyone because he left it in the car. So why have there been no reports of an additional rifle being recovered from the scene? This missing rifle is the only weapon whose wounds examiner Wayne confirmed as having killed the children. In other words, the primary murder weapon should be considered missing.