TALLAHASSEE, Fla. — Florida Gov. Rick Scott announced plans Friday to put more armed guards in schools and to make it harder for young adults and some with mental illness to buy guns, responding to days of intense lobbying from survivors of last week’s shooting at Marjory Stoneman Douglas High School.

Scott unveiled his school safety proposals as teachers returned for the first time to Stoneman Douglas since the shooting Feb. 14 killed 17 people.

The shooting sparked an intense push to restrict access to assault rifles fueled by student activists who swarmed the state Capitol demanding concrete gun control measures.

President Donald Trump said repeatedly Friday that he favored arming teachers to protect students, an idea many educators rejected out of hand.

“I am totally against arming teachers,” Broward schools Superintendent Robert Runcie said. “They have a challenging job as it is.”

Scott, a Republican widely expected to run for the Senate, outlined his plan at a Tallahassee news conference.

In addition to banning firearm sales to anyone under 21, the governor called for a trained law enforcement officer for every school — and one for every 1,000 students at larger schools — by the time the fall 2018 school year begins.

Stoneman Douglas in Parkland, which has more than 3,000 students, had one armed resource officer who never entered the building under attack while a gunman was shooting people inside, officials said.

At least two other Broward sheriff’s deputies may have also waited outside Stoneman Douglas while the killer gunned down people, according to other officers on the scene.

The sheriff’s office is investigating the claims from Coral Springs cops, Sheriff Scott Israel told the South Florida Sun-Sentinel on Friday.

Those failures were compounded by confusion about what was being shown to police on school security cameras the day of the shooting and the lack of meaningful response to reports to the FBI and local police that suspect Nikolas Cruz, 19, might become violent, had guns and possibly would attack a school.

Cruz is jailed on 17 counts of murder and has confessed to the shootings, investigators say.

The governor’s $500 million plan would create a “violent threat restraining order” that would let a court prohibit a violent or mentally ill person from buying or possessing a firearm or other weapon under certain circumstances.

The proposal would also strengthen gun purchase and possession restrictions for mentally ill people under the state’s Baker Act, which allows someone to be involuntarily hospitalized for up to 72 hours.

Scott is seeking $50 million for mental health initiatives that include expanding services by providing counseling, crisis management and other mental health services for youth and young adults.

“No one with mental issues should have access to a gun. It is common sense. It for their own best interest, much less the best interest of our communities,” Scott said.

But the legislature’s Republican leadership proposed letting teachers carry a gun if they have had law enforcement training — a provision that House Speaker Richard Corcoran called a “game changer.”

The legislators’ plan also calls for a three-day waiting period for most gun purchases, with exceptions.

Democrats said neither plan goes far enough.

“Unfortunately, both plans omit a third, critically important piece of legislation Democrats have been and continue to push for — a ban on assault weapons and high capacity magazines,” said state Senate Democratic Leader Oscar Braynon.

Talia Rumsky, a 16-year-old Stoneman Douglas student who was at school during the shooting, was among those who traveled to Tallahassee on Wednesday to lobby lawmakers about gun control.

She said Scott’s plan to make it illegal for anyone under 21 to purchase a gun is a start, but said she doesn’t think it goes far enough.

Meanwhile, teachers began the emotionally fraught process of returning to the school Friday to collect belongings from classrooms that have been off-limits since the slayings.

Following an orientation Sunday for teachers and students, classes resume next week.