They were joined by thousands of students in Chicago, Washington D.C., Silver Spring in Maryland and other districts shouting and marching in solidarity.
Despite the peaceful protests, administrators in Texas and Virginia warned students they could be suspended if they participated in a walkout.
Needville High School issued a statement claiming "all will be suspended for three days" regardless of how many students protested.
"Life is all about choices and every choice has a consequence whether it be positive or negative. We will discipline no matter if it is one, fifty, or five hundred students involved," a statement by Superintendent Curtis Rhodes said on Facebook.
"Please be advised that the Needville ISD will not allow a student demonstration during school hours for any type of protest or awareness.
"Should students choose to do so, they will be suspended from school for 3 days and face all the consequences that come along with an out of school suspension."
The post has since been deleted.
Teenagers who survived last week's mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, rallied in the state capital Tallahassee.
They were holding signs reading "Never Again" and "Be The Adults, Do Something".
"No longer can I walk the halls I walked millions of times before without fear and sadness," Stoneman Douglas student Florence Yared, 17, told a crowd at the Capitol which included thousands of supporters.
"No longer can I walk the halls without imagining bloodstains and dead bodies.
"All because of the damage that a single AR-15 rifle caused."
Lorenzo Prado, also a junior at Stoneman Douglas, said he was there "to demand change from my government".
"To let these victims lives be taken without any change in return is an act of treason to our great country," Mr Prado said, his voice choked with emotion.
Rallying in solidarity and inspired on social media by the activism of their peers, students staged walkouts from other high schools in Florida and elsewhere vowing to make the tragedy a turning point in America's deadlocked debate on gun control.
Hundreds of students descended on city hall in Minneapolis, Minnesota, and marched in other cities, including Chicago, the midwestern metropolis wracked by gun violence.
"The students were really enthused about making the connection between what happened in Florida, other school shootings, and the gun violence that they experience on a day-to-day basis here in Chicago," Kofi Ademola, who works at the Youth Connection Leadership Academy in Chicago, said.
'NRA has got to go'
In Washington D.C., hundreds of students gathered outside the White House chanting slogans against the National Rifle Association (NRA), the powerful gun lobby, and demanding action from Mr Trump.
"Hey hey, ho ho, the NRA has got to go," they chanted.
A girl with a megaphone read out the names of the 14 students and three teachers killed at Stoneman Douglas as the crowd of students held their arms up in the air.
Faced with the outpouring of grief and outrage over the Florida shooting, Mr Trump met with parents, students and teachers at the White House on Wednesday.
Students are also planning a march on Washington next month. The March for Our Lives is scheduled to take place on March 24, with sister rallies planned across the country.
- with AFP