Mexican police and protesters clash at Oaxaca university

OAXACA, Mexico -- Federal police surrounded a university packed with leftist protesters yesterday in conflict-ridden Oaxaca, clearing barricades and firing tear gas as the activists showered them with gasoline bombs.

At least 20 protesters, 10 officers, and three news photographers were injured in the clashes.

About 200 police in body armor with riot shields advanced to the university gates and fought the protesters for more than six hours before they finally retreated.

Under Mexican law, the university rector must give the police permission to enter. Rector Francisco Martínez, speaking on the university radio station, called the operation an "attack" and demanded the police withdraw.

The federal police said they simply intend to "restore order and peace" on the streets and did not plan to storm the school.

Protesters were seen running from the campus and lobbing gasoline bombs packed with nails, stones, and firecrackers at police.

Officers responded with water cannons and rounds of tear gas, supported by helicopters and armored vehicles. Some officers also picked up rocks and bottles and hurled them back at protesters.

A free medical clinic near the university reported that more than 20 protesters had been treated for bruises, cuts, and injuries caused by tear gas.

The university radio station reported that at least six demonstrators had been arrested, and the station demanded their release.

The university is a stronghold of the movement to oust Oaxaca Governor Ulises Ruiz, who is accused of rigging the 2004 election to win office and of organizing bands of thugs to attack dissidents. At least nine people have died in the conflict, most protesters shot by police or armed gangs. The embassies of the United States , Canada, Britain, France, and Germany have warned their citizens to avoid traveling to the region.