Local news reports said that "tens of thousands of students" were taking part in the protest that was spreading through schools across the country's second largest city ahead of a US Senate debate on a divisive immigration reform bill.
The latest demonstration came after one of the biggest protests in recent US history on Saturday when more than 500,000 people marched in Los Angeles against the immigration reform bill that would make it a felony criminal offence to be in the United States illegally.
Smaller protests took place in a number of cities around the country as well over the weekend and on Monday against the draft laws.
Los Angeles pupils pursued the protest Monday by walking out of class, prompting education officials to lock down some campuses to keep students inside.
But they leaped fences and marched through streets brandishing US and Mexican flags and chanting slogans against the immigration bill.
"If we don't leave school today, half of the school who don't have papers will have to leave soon if this law passes, and they won't come back, ever," shouted Huntington Park High School student Anita Benitez.
The Los Angeles Police Department put officers on a "citywide tactical alert" as a precaution because of the wave of protests that included a crowd of at least 1,500 students who were demonstrating outside city hall.
The protests target a bill, already passed by the US House of Representatives, that would crack down on employers hiring illegal workers and people smuggling illegal immigrants into the country.
The bill would also require employers to verify social security numbers with the Department of Homeland Security, beef up penalties for immigrant smuggling and stiffen penalties for undocumented immigrants who re-enter the US after being deported.
At least 11 million illegal immigrants, most of them from neighbouring Mexico, live in the US and are responsible for a huge part of the work force.
Bush defends migrants
But US President George W Bush is pushing for a relaxation of immigration laws.
His plan would allow many undocumented workers to register for legal status on a temporary basis, and ultimately, if they qualify, for US citizenship.
The president defended his immigration reform plan against conservatives who want tougher measures.
"This program would help meet the demands after growing economy and it would allow honest workers to provide for their families while respecting the law," he said.
But senior members of his Republican Party remained divided however over how to tackle immigration reform.
Mr Bush attended a swearing-in ceremony on Monday for nearly three dozen new US citizens to underscore the hope and vitality that new arrivals immigrants bring to the country.
"Our immigrant heritage has enriched America's history. It continues to shape our society (and) ... brings renewal to our national character," Mr Bush said.