MEXICO CITY (AP) — Teachers angry over the passage of a national education reform blocked the main approach to Mexico City's airport for more than eight hours Thursday, forcing many people to leave their cars and rush through the streets on foot to catch flights.

The teachers marched to the area in northern Mexico City around noon and shut down a busy highway, causing traffic to back up for miles (kilometers) and increasing simmering public anger at the weeks of teacher protests.

Protesters lifted the blockade in the evening after their leaders asked them to go back to the Zocalo, Mexico City's central plaza, where they have been camping for weeks.

Hundreds of police guarded the airport to prevent the members of a dissident teachers union from blocking other entrances. Airport management advised passengers to take alternate routes to the airport, including the subway.

Airport administrators used federal police pickup trucks and other vehicles to transport passengers stranded by protesters.

Some airlines, including Aeromexico and Interjet, announced they would not charge any fees to people who changed their travel times or missed flights.

The teachers, mainly from poor southern states, are protesting a just-approved measure that could break union control over the public education system.