Sandy Hook School Shooting

Police cars and other vehicles fill a road near the scene of a mass school shooting at Sandy Hook Elementary School on December 14, 2012 in Newtown. (Mario Tama, Getty Images / December 14, 2012)

As the first Newtown officers arrived at the Sandy Hook Elementary School at 9:39 a.m. last December, gunshots boomed from inside the school.

One officer parked behind the school, and three others were near the school's baseball field. The first officers entered the school at 9:44:47, nine minutes after the initial 911 call.

The police response, including how much time it took to arrive at and to enter Sandy Hook Elementary, is expected to be the subject of scrutiny from town officials and outside public safety experts. Police have defended their actions as appropriate given the chaotic situation they faced. In his just-released investigative summary, State's Attorney Stephen Sedensky III concluded that the police actions were appropriate.

Experts interviewed about the response had differing opinions. One expert not related to the case told The Courant he believed officers should have gone straight in the school as soon as they arrived to either subdue or distract the shooter. Another concluded that the amount of activity outside the school, some connected to uncertainty about whether there were other shooters, would have made an immediate entry difficult.

Law enforcement from all over the country will be reviewing the police response to the Newtown shooting, said Peter Valentin, a criminal justice professor at the University of New Haven.

"It is important to dissect all of the information and to be critical if it is warranted," Valentin said. "I am sure there will be some disagreements about what Newtown did — right or wrong."

The scrutiny, which will include a departmental review and a Newtown Police Commission examination, is likely to focus on the initial response time of more than three minutes and the decisions made by officers once they arrived at the school.

The summary released Monday revealed that Adam Lanza entered the school by shooting through a front window, and shot and killed Principal Dawn Hochsprung and school psychologist Mary Sherlach. The first 911 call came from the school at 9:35:39.

Officer Michael McGowan was the first to respond, at 9:39. McGowan parked his cruiser behind the school, the report shows. The records indicate that the first officers at the scene heard gunshots.

Thirteen seconds later, Newtown Sgt. David Kullgren and Officers William Chapman and Scott Smith arrived on the street leading to the school, Dickinson Drive, drove up the road and parked near a dugout of the school's baseball field, just off to the side of the school, according to the report. As those officers exited their vehicles, Sandy Hook school staff members were calling 911 and, with gunshots crackling in the background, pleading for help.

Lanza apparently shot and killed himself at 9:40:03, one minute after the first Newtown officer arrived, the report states

The chaotic scene outside the school included parents, who arrived to help a class make gingerbread men, running through the parking lot. Two women hid behind a Dumpster just behind Lanza's car and called 911, the report states. Another man ran toward the nearby playground after hearing gunshots, where he was "proned out" by McGowan at 9:41:24. At least six officers responded to McGowan's call for assistance to detain the unidentified man.

Upon their arrival, Chapman and Smith conducted a perimeter search of the school. Newtown police entered the school at 9:44:47 with two three-man teams. One entered from the rear of the school and the other from the boiler room.

Newtown Police Chief Michael Kehoe told the Danbury News-Times that his department will do an "after-action" shooting review once the entire state police report is released, which is expected to be in the next few weeks.

One expert said officers are trained to find a shooter as fast as possible.

"Six minutes is a lifetime in a shooting situation. The first officer should have been running into the building and the officers following worry about security,'' said Vincent Riccio, a former New Haven police officer who now runs a private security firm focusing on school security.

But School Safety Expert Kenneth Trump said the amount of activity going on outside would have made it difficult for officers to proceed. Trump is a proponent of locking down schools and classrooms during an active shooting situation rather than evacuating people.

"You have to approach this with the thought there's multiple shooters and anyone you encounter could be a potential shooter and that is going to delay or obstruct the police,'' Trump said.

State police troopers arrived at 9:46:23 and entered the school through the glass window Lanza had blasted out, the timeline shows.

Two of those troopers, along with Chapman and Smith, entered teacher Victoria Soto's room at 9:51:31. Smith indicated that "we've got one suspect down," shortly after.