Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Three deputies from the Broward County Sheriff's Office remained outside the freshman building of Marjory Stoneman Douglas High in Parkland, Florida, during one of the nation's deadliest school shootings, two law enforcement sources confirmed to NBC News Saturday.

While the reason they remained outside is currently unclear, experts say it's highly unusual for a police officer to stay on the sidelines of an active shooting scene and not try to neutralize the threat.

The detail about the Broward County deputies came after reports emerged Thursday that Douglas High's armed and uniformed resource officer Scot Peterson did not enter the freshman building and attempt to stop the gunman during the attack.

Related: Fight, flight or freeze? Officers rarely fail to confront threat, experts say

Broward County Sheriff Scott Israel said Thursday that Peterson was seen on video arriving at the west side of the freshman building, but "he never went in." Israel said Peterson should have gone in and “addressed the killer, killed the killer,” adding the fact that he didn’t left him “devastated.”

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

“There are no words, I mean these families lost their children,” Israel said. The sheriff added that Peterson was suspended without pay, pending an internal investigation, before later resigning.

David Hogg, a Stoneman Douglas senior and survivor of the shooting, said he's met Peterson and he thinks the fact that the officer didn't take action, even though he was armed, illustrates that simply having a gun won't stop a shooting.

"He, just like every other officer out there, at heart, is a good person," Hogg said. "Who wants to go down the barrel of an AR-15, even with a Glock? And I know that's what these police officers are supposed to do, but they're people too."

President Donald Trump, who proposed arming teachers as a means to prevent school shootings, criticized Peterson for remaining outside.

"He didn't turn out to be too good, I'll tell you that," Trump said at the Conservative Political Action Conference, calling the guard "not a credit to law enforcement" and adding that he didn't "love the children."

Related: Trump: An armed teacher 'would've shot the hell out of' the Florida gunman

Trump on Saturday doubled down on his suggestion to give "adept" educators firearms and a yearly bonus.

Armed Educators (and trusted people who work within a school) love our students and will protect them. Very smart people. Must be firearms adept & have annual training. Should get yearly bonus. Shootings will not happen again - a big & very inexpensive deterrent. Up to States. — Donald J. Trump (@realDonaldTrump) February 24, 2018

Douglas High teacher Felicia Burgin, who was inside the building while the shooting occurred, said she believes Peterson is being used as a "scapegoat."

"People are angry right now. They're angry, they're hurting and now all their hurt is being directed in, to me, the wrong direction," she said. "You want to be angry? Be angry at the gunman who killed all these people. Be angry at the gun laws that allow these guns to be purchased by 18 year olds."

A spokesman for the Coral Springs police department Friday praised the "countless deputies and officers" who were among the first responders to the tragedy, calling their actions "heroic."

"As already reported, any actions or inactions that negatively affected the response will be investigated thoroughly, and the information will be released officially from the proper agency spokesperson," the Coral Springs police department statement said.

The FBI admitted two days after the shooting that they had received a tip on Jan. 5 warning that the alleged gunman Nikolas Cruz expressed erratic behavior, owned guns, and had a "desire to kill people."