Broward County Schools superintendent Robert Runcie said about 95 percent of the student body returned to Marjory Stoneman Douglas High School Wednesday, two weeks after a mass shooting killed 17 people. He said the school has 3,293 students, and he called Wednesday's attendance "outstanding."

The school day ran on a "modified schedule" from 7:40 a.m. to 11:40 a.m. -- the same schedule that will be in place for the rest of the week, he said. Runcie also said only about 15 students and four of the 215 employees have inquired about transferring to other schools.

Runcie said there were about 150 counselors at the campus to offer support to staff and students, as well as 40 therapy dogs. Almost all of the county's high school principals also came to the school to support the staff.

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"In the beginning, everyone was super serious, but then everyone cheered up and it started being the same vibes we had before the shooting. People started laughing and joking around," said Kyle Kashuv, a junior who said he hugged every single teacher.

He was amazed by the outpouring of support from the community including the police presence, animals and well-wishers. There were letters from all over the world and "banners on every single wall," he said.

Runcie said he would use the words "flexible, support and love" to describe what's happening at the school this week. He added that a heavy law enforcement presence will be at the school for the remainder of the year.

Students were greeted Wednesday by police officers carrying military style rifles, which rattled some students.

"This is a picture of education in fear in this country. The NRA wants more people just like this, with that exact firearm, to scare more people and sell more guns," said David Hogg, who has become a leading voice in the students' movement to restrict assault weapons.

Students wait at a crosswalk as they arrive to attend classes at Marjory Stoneman Douglas High School on February 28, 2018 in Parkland, Florida. Joe Raedle/Getty Images

The students had missed two weeks of school following the attack that took place in a freshman building just before dismissal. The suspect, 19-year-old Nikolas Cruz, is in the Broward County Jail, charged with 17-counts of first-degree murder.

"The past two weeks have certainly been a challenge," Runcie said Wednesday. "To say that it has been emotional, heartbreaking and overwhelming would certainly be an understatement."

The shooting has thrust many of the surviving students into the center of the nation's gun debate.

"We continue to be inspired and amazed at our students and how well they responded to this, how they provided leadership on a national level to bring attention to some very salient issues that have emerged out of this tragedy," Runcie said.

Many students said the debate over new gun laws has helped them process the traumatic event and prepared them to return.

Alexis Grogan, a 15-year-old sophomore, was concerned that it might be too soon to go on as usual without slain friends such as Luke Hoyer, who sat two seats behind her in Spanish class. But the students' effort to strengthen gun laws has buoyed her spirits.

"I am so proud of how the kids at my school have been fighting because we all want change to happen and, as we see the progression, it really shows us that people do care. And they do hear what we have to say," Grogan said in a text message.

As students went back to class, Dick's Sporting Goods, a major U.S. retailer, announced that it would immediately halt sales of assault-style rifles and high-capacity magazines at all of its stores and ban the sale of all guns to anyone under 21.

On Tuesday, victims' relatives kept up the pressure in Florida's capital, offering emotional testimony before a House committee that voted in favor of a bill to raise the minimum age to buy long guns from 18 to 21 and to create a program allowing teachers to carry concealed weapons in classrooms if their school district allows it. Those teachers would receive law-enforcement training and get deputized by the local sheriff's office.

State lawmakers continued their investigation of how the suspected shooter, Cruz, managed to slip through local law enforcement despite previous warning signs.

The Florida House voted Wednesday to subpoena records from Broward County and the school board, as well as sheriff's offices in Broward and Palm Beach counties and the city of Coral Springs. The subpoenas demand that the records be turned over by Tuesday.

Florida Gov. Rick Scott said he hopes a gun and school-safety bill is passed before the annual legislative session ends March 9. The measures he proposed did not include arming teachers, but he declined to say Tuesday whether he would veto a sweeping package that includes that provision.

The Broward superintendent has spoken out firmly against the idea of arming teachers.

Marion Hammer, a lobbyist for the National Rifle Association and Unified Sportsmen of Florida, said she supports school security and keeping guns out of the hands of the mentally ill, but "guns are not the problem."

Kyle Kashuv said he was most moved by a tattoo his teacher got that said "MSD Strong" with a giant eagle.

"The shooting doesn't define us," Kashuv said. "We're really moving past it and trying to heal right now."