Survivors of the deadly shooting have returned to school in Florida, as people in Pennsylvania attend a church service to bless their assault-style rifles.
Students in the second-deadliest US public school shooting were brought to tears by empty seats and missing names at roll call on Wednesday, two weeks after 17 students and educators were massacred.
Upon emerging from a half-day of classes intended to ease their return after the tragedy on February 14, some of the roughly 3000 teens who attend Marjory Stoneman Douglas High School in Parkland, Florida, described their emotional day.
Samuel Safaite, a 15-year-old sophomore, said students in his Spanish class broke down when the teacher took attendance and read out the name of Luke Hoyer, a 15-year-old slain in the attack.
"A lot of people started crying because we all knew he was gone," Safaite said. "It was difficult for a lot of people."
Many of the students carried white flowers when they arrived at the school in the morning and wove through hundreds of uniformed police officers providing security for their return. Emotional-support dogs also were on hand to provide comfort.
Nikolas Cruz (19), who had been kicked out of the school for disciplinary reasons, is accused of carrying out the rampage.
As school shootings become a growing concern, police in Georgia on Wednesday arrested a high school teacher who barricaded himself inside a classroom and fired a handgun when the principal tried to force the door open.
The Florida shooting inflamed the nation's long-running debate on gun rights as defined in the Second Amendment of the US Constitution. It also sparked a youth-led gun control movement featuring survivors of the attack, who have already lobbied lawmakers in Florida's capital Tallahassee and Washington, D.C.
"We will push for change and our children are going to be the change agents," said Jeannine Gittens (44), who drove to the school to be there to meet her son Jevon, a 16-year-old junior, when he arrived on the bus. "We see that things have to change and we are not going to stop until they do."
The building where most of the victims died was closed, surrounded by a chain-link fence decorated with signs reading "MSD strong" and "Pray for Douglas." Florida lawmakers are contemplating tearing it down and replacing it with a memorial to the victims.
As she left the school with her mother and 18-year-old brother, sophomore Marisa Lopez (16) said some friends were talking about leaving the school.
"I don't think that some people are ready to move on," Lopez said, adding that some of her friends had witnessed the shooting of Scott Beigel, a 35-year-old social science teacher who was one of the three adults killed in the attack. "I just don't know if some of them are ever going to get over it."
Investigators say Cruz used a legally purchased AR-15 assault-style rifle in the attack.
The Republican leaders of the US Congress on Tuesday rejected new limits on guns after the attack. The powerful National Rifle Association lobbied forcefully against any restrictions on gun sales, saying they infringe on the rights of law-abiding citizens.
AR-15 RIFLES BLESSED
In Pennsylvania, hundreds of couples toting AR-15 rifles packed a Unification church on Wednesday to have their marriages blessed and their weapons celebrated as "rods of iron" that could have saved lives in a recent Florida school shooting.
Women dressed in white and men in dark suits gripped the guns, which they had been urged to bring unloaded to the church in the rural Pocono Mountains, about 160km north of Philadelphia.
Many celebrants wore crowns - some made of bullets - while church officials dressed in flowing bright pink and white garments to go with their armaments.
A spokesman for the church, now headed by the Reverend Hyung Jin Moon after the death of his father and church founder, the Reverend Sun Myung Moon, said the marriage blessing ceremony had been planned long before the Florida high school shootings.
Students from an elementary school near the church were relocated for the day to distance them from the gun-toting couples at the ceremony, according to the Wallenpaupack School District website.
Moon said in a statement that the staff of the Florida school should have been armed, an option President Donald Trump has said should be explored nationwide and which teacher unions have criticised.
"Each of us is called to use the power of the 'rod of iron' not to arm or oppress as has been done in satanic kingdoms of this world, but to protect God's children," he said, citing the Book of Revelation in the Bible.
"If the football coach who rushed into the building to defend students from the shooter with his own body had been allowed to carry a firearm, many lives, including his own, could have been saved," Moon's statement said.
The Pennsylvania school district three years ago called off classes during the massive manhunt for survivalist Eric Frein, who police said used an AK-47 style weapon to ambush a Pennsylvania state trooper barracks and then fled into the mountains.
Frein was found guilty in April of killing a Pennsylvania state trooper and wounding another in the September 2014 attack.
