PARKLAND, Fla. (CBSNewYork/AP) — More questions are being raised about the initial response to Florida’s deadly school shooting.

There are new reports that at least three Broward County sheriff’s deputies failed to enter the school as the gunman killed 17 people inside.

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CBS News has learned that Coral Springs police officers say they arrived at Marjory Stoneman Douglas High School shortly after the shooting and found the deputies outside with guns drawn. The Broward County sheriff’s office says it is investigating the claims.

A fourth deputy, school resource officer Scot Peterson, resigned earlier this week. Sheriff Scott Israel said Peterson took a defensive position outside the school during the shooting.

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Meanwhile, chilling new details have emerged from a call made to the FBI tip line preceding the deadly Valentine’s Day shooting.

The agency says it failed to act after a woman close to the suspect told investigators “I know he’s going to explode.” The revelation comes as the debate rages on how to prevent similar gun violence in American schools.

The woman says she saw one warning sign after the next in 19-year-old Nikolas Cruz, saying he had the mental capacity of a 12 or 13-year-old with a growing arsenal of guns and an uncontrollable temper.

She says she feared something could lead him to “getting into a school and just shooting the place up.” Now, people across the nation are demanding change.

“You failed us,” Marjory Stoneman Douglas survivor Samantha Fuentes said, directing harsh words at Peterson. “You took an oath, and you broke your promise.”

On Friday, President Trump further pushed his controversial proposal to arm teachers with guns.

“A security guard doesn’t know the children, doesn’t love the children,” he said. “You have to be adept. I’m not talking about every teacher, I’m talking about a small percentage.”

In one Ohio county, the sheriff said he had over 300 teachers sign up in less than eight hours, all wanting to be trained in firearms. Meanwhile, the very teachers who lived through the February 14th nightmare say no way.

Broward County Schools Superintendent Robert Runcie denounced the idea, saying he’s “totally against arming teachers.”

In New York, lawmakers share his sentiment.

“They’re trying to distract us from the reality of the matter,” Governor Andrew Cuomo said. “Giving a teacher a gun suggests the only thing we need to worry about is a gun attack at a school. Not true.”

Florida’s governor has proposed raising the age to purchase an assault rifle to 21. On Saturday, the Congressman who represents Parkland called for action.

“Nearly 20 years since Columbine, we continue to suffer a mass gun violence problem that is uniquely American. The rest of the developed world has fixed this and saved lives,” said Rep. Ted Deutsch.

The debate continues as many wonder how Cruz was able to commit mass murder after several tipsters alerted authorities. In a more 13 minute call to the FBI, a woman close to the confessed gunman revealed his threatening social media posts, his arsenal of weapons, and his desire to kill, saying, “I just want to, you know, get it off my chest in case something does happen, and I do believe something’s going to happen.”

Starting next week, school resources officers in Broward County will be armed with semi-automatic weapons. The superintendent says it’s a temporary move mean to help safeguard against a possible copycat attack as high school students get set to return to class Wednesday.

Students can go back to campus Sunday for counseling and orientation.

“We’re going to try and get back to as normal as possible and really take care of the kids. That’s the bottom line,” teacher Jim Gard said.

Meanwhile, several companies are cutting ties with the National Rifle Association.

United Airlines tweeted it’s “notifying the NRA that we will no longer offer a discounted rate to their annual meeting.” Enterprise, Hertz, MetLife and others have also ended relationships with the association.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)