NEW YORK (AP) — About 1,000 New York City high school students chanted ‘‘This is what democracy looks like!’’ and waved homemade signs and banners Friday as they marched across the Brooklyn Bridge to protest a plan to eliminate their free transit passes.

The students walked out of classrooms all over the city at noon and converged at City Hall Park for a rally with elected officials and transit union members.

Then they marched across the bridge for a second rally near the former headquarters of the Metropolitan Transportation Authority in Brooklyn.

Fernando Matos, 17, a student at Samuel Gompers High School in the Bronx, said that without a free transit pass he would have to transfer to a different school.

‘‘I do not want to go to a local high school,’’ Matos said. ‘‘It doesn’t have the classes I need.’’

The protest comes a day after Mayor Michael Bloomberg announced a stepped-up effort to fight truancy.

Bloomberg said Friday that the students should have stayed in class.

‘‘If I were them, I’d just think long and hard someday,’’ he said. ‘‘If I didn’t pass a test, I’d always go back and wonder, ’Was it that afternoon when I was trying to be cute and be out there and picketing was better than being in class?’’’

More than 500,000 city students receive free or reduced-fare MetroCards to get to and from school.

The transportation agency has proposed ending the free rides as part of its effort to close an $800 million budget gap.

The city contributed $45 million to the program last year while New York State paid only $6 million.

Bloomberg said the protesting students should demand that the state Legislature kick in more.

‘‘We are not going to make up for the state,’’ he said in his weekly radio address. ‘‘We just cannot do that.’’

Without the free passes, families would be forced to buy monthly MetroCards at a cost of about $1,000 a year per child.

‘‘That’s money you’re taking away from buying them books,’’ said Debbie Officer, a mother of two from Brooklyn who joined the protest.

Vladimir Edouard, 16, who attends the School for Democracy and Leadership in Brooklyn, said his parents would have to sacrifice to pay for his MetroCard.

‘‘My mom would probably have to get a second job to pay for my sister and I to get to school,’’ he said.

Sharon Litaker, a special education teacher at Banana Kelly High School in the Bronx, attended the rally to support her students.

‘‘I just walked out,’’ she said. ‘‘A lot of families lost their jobs. They don’t have the extra income to pay for their children’s MetroCards.’’

The rally was organized by a group called the Urban Youth Collaborative. The students took up half the length of the bridge as they marched to Brooklyn shouting ‘‘The students, united, will never be defeated!’’ Drivers honked their horns and cheered as the students spilled off the bridge and into Brooklyn.

A spokesman for the Department of Education said that any disciplinary action the students might face for cutting class would be up to their principals.

The citywide high school attendance rate Friday was a lower-than-usual 69.8 percent. New York City public schools students were off Thursday for a staff development day, and many may have taken a four-day weekend.