Students and school staff across the US are commemorating the Florida school shootings with a walkout, exactly one month after the killings.
They are stopping lessons for 17 minutes in memory of the 17 people killed at Marjory Stoneman Douglas High School.
Pupils at the school, which was targeted by a former pupil, hugged each other on the football field.
Protest organisers accuse Congress of failing to tackle gun violence.
The White House revealed a plan this week to deter school shootings which does not include President Donald Trump’s repeated calls to raise the age for buying semi-automatic rifles to 21.
Instead, it moves ahead with his controversial proposal to provide firearms training to school employees.
How is the protest unfolding?
The walkouts began at 10:00 (10:00 EST is 14:00 GMT) across America’s time zones.
Organisers of the National School Walkout, who were also behind the Women’s March in January 2017 against Mr Trump’s inauguration, called on “students, teachers, school administrators, parents and allies” to take part.
“Parents have the right to send their kids to school in the mornings and see them home alive at the end of the day,” they say.
“We are not safe at school. We are not safe in our cities and towns. Congress must take meaningful action to keep us safe and pass federal gun reform legislation that address[es] the public health crisis of gun violence.”
In Parkland, families and supporters applauded as thousands of students slowly marched on to the Stoneman Douglas school football field.
School principal Ty Thompson called on them to stage the “biggest group hug”.
In New York, hundreds of students from Fiorello H LaGuardia High School – many dressed in orange, the colour of the gun-control movement – took to the streets of Manhattan.
“Thoughts and prayers are not enough,” read one sign.
New York Governor Andrew Cuomo also joined protesters for a symbolic “die in” – lying down in a street in Lower Manhattan.
The disruption to the school day is opposed by some schools, notably in one Texas district where students who walk out have been told they face a three-day suspension.
“We will discipline no matter if it is one, 50, or 500 students involved,” said Needville schools superintendent Curtis Rhode.
What happened in Parkland?
The attack on Valentine’s Day, 14 February, was the deadliest US school shooting since 2012.
The former pupil arrived on campus and began shooting students and staff before abandoning the weapon and escaping, according to court documents.
Fourteen students and three members of staff died.
US prosecutors are seeking the death penalty for the attacker who has been charged with 17 counts of premeditated murder and 17 counts of attempted murder.
How have the authorities responded?
The US House of Representatives is due to vote this week on a bill to fund greater security in schools but it does not address gun control.
In its action plan, the White House proposed to:
- Fund programmes to train school staff to use firearms
- Encourage military veterans and retired police officers to become teachers
- Improve background and mental health checks
In addition, a new federal commission on school safety will examine the age limit issue.
Chuck Schumer, leader of the opposition Democrats in the Senate, dismissed the White House’s action plan as “baby steps”.
When the state of Florida passed a gun control law which raises the legal age for buying rifles to 21, it was sued by America’s main gun lobby, the National Rifle Association, which argues that such curbs violate the US constitution.
In a separate incident, a teacher in California is believed to have accidentally fired a gun in a classroom on Tuesday, injuring a student.
Police said the teacher at Seaside High School, in Monterey County, had been taking a public safety class when he accidentally discharged the weapon into the ceiling.
Officials said one student was injured by either bullet fragments or ceiling debris and was taken to hospital for treatment
The teacher has been placed on administrative leave and the incident is being investigated, police said.