Chanting, ", se puede," ("Yes, we can") and carrying "Latino Power" signs, hundreds of Northern Virginia high school students demonstrated for a second day yesterday against legislation that would crack down on illegal immigrants.

In Prince William County, about 350 students protested outside Freedom High School in Woodbridge. In Fairfax County, dozens of students marched out of JE.B. Stuart High School and into Arlington County, where they stopped at two more high schools, adding students at each stop.

Opponents of the legislation have demonstrated across the country, including 500,000 people in Los Angeles on Saturday. The legislation, passed by the House of Representatives, would make it a felony to be in the United States illegally and make it a crime to help illegal immigrants.

The Fairfax march started at Stuart High in the Falls Church area about 9 a.m. "We started getting bigger, so we left the school," said Louie Martinez, 16, a sophomore at Stuart, whose student body is 40 percent Latino. "We were like, 'We'll just keep walking.' We're showing the government we're big."

The group marched to Wakefield High School and then, followed by police cars that blocked traffic, marched several miles up George Mason Drive to Washington-Lee High School.

After police told them they would be arrested if they strayed onto the Washington-Lee campus, the protesters demonstrated at a park across the street.

The school's doors were locked to prevent outsiders from entering, and at noon Principal Gregg Robertson announced that students who left would have unexcused absences. Still, about 40 students left to join the protest, which swelled to around 200 people.

School officials did not try to stop them. "Part of the Washington-Lee mission is to encourage students to take an active role in their community," Robertson said. As with earlier demonstrations, word of the protests was spread by cellphone and the Web site MySpace.com. Some students said they learned about the immigration debate from newspapers or in class. Others said friends convinced them that many of the proposals were unfair.

Raeshwan Greene, 17, a senior at Wakefield, which is 43.7 percent Latino, said: "Half of my friends came here a few years ago. . . . People have forgotten the meaning of America."

Caitlin Thomson, 17, a junior at Wakefield, said: "These people have worked really hard to get here. There might be economic problems or a dictatorship. People want to be free and have a new life. That's what we learn in history class."

Some had more personal connections to the issue. Ephram Lopez, 16, a sophomore at Stuart, is U.S.-born, but he worries that his mother, a baker, could be sent back to her native Guatemala.

"They are trying to deport her," Lopez said. "It's going to take her away from me and my two little brothers."

Lopez said everyone's quality of life in the Washington area is improved by immigrants. "We work at fast food restaurants. We paint houses. We mow lawns. Most people work without papers."

In Prince William, in addition to students from Freedom High School, many young people waving Mexican and El Salvadoran flags said they were from C.D. Hylton, Gar-Field and Woodbridge high schools, all in the eastern section of the county, where many Latinos live.

The students marched down Route 1 to Todos Supermarket, operated by Carlos Castro, a Salvadoran immigrant.

Arlington County Board member Walter Tejada (D), who joined the demonstration at Washington-Lee, said the students had been "itching to have their voices heard."

"They know that this bill unfairly cuts the legs of the working immigrant community," he said.

Christian Dorn, 16, a Salvadoran and a junior at Potomac High School in Dumfries, said the demonstrations had proved something.

"It got the word out that we're not going to be quiet," she said. "It's similar to what the African Americans did in the 1960s. . . . We shouldn't be treated like criminals."

Staff writers Ian Shapira and Jamie Stockwell contributed to this report.