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Yeshiel Panchia, Associated Press
A car burns outside a nightclub near the University of the Witwatersrand in Johannesburg, South Africa, Friday, Oct. 14, 2016. Cars were set alight and businesses damaged as chaos erupted after a curfew was instituted at the university, where police released tear gas to prevent protesters on campus from setting gas canisters alight.

JOHANNESBURG — South African police arrested nine people during arson attacks and stone-throwing near a Johannesburg university where students have been protesting for free education, authorities said Saturday, and the government called for "violent campus protest to stop immediately."

Two vehicles were set on fire in the overnight unrest in Braamfontein, an urban area that was the scene of similar violence during clashes between students and police earlier in the week, the national police said on Twitter.

Of the nine people arrested, two are students at the University of the Witwatersrand, also known as Wits, two are from other universities and five are not students, said Shirona Patel, a university spokeswoman.

The school, one of South Africa's leading universities, has imposed overnight restrictions on access and movement on campus because of security concerns. It rejected criticism from some protesters that additional security measures and a police presence on campus were provoking violence.

"The only reason these measures were implemented was because a group of students started four fires on our campuses on Thursday night, smashed windows, stoned buildings and flooded rooms," the university said in a statement Saturday.

In other violence, two buildings were damaged by firebombs at the Howard College campus of the University of KwaZulu-Natal, South African media reported Saturday.

The government statement on Saturday called the upsurge of violence around the student protests "criminal and unwarranted."

Student protests, many of which have turned violent, have forced some universities to close. The unrest began last month when the government recommended that universities increase 2017 fees by no more than 8 percent, while saying it would cover fee hikes for poor university students.

Protesters call the plan insufficient and demand the gradual implementation of free university education.

Follow Christopher Torchia on Twitter at www.twitter.com/torchiachris