Maiduguri, Nigeria ? Nigerian Muslims protesting caricatures of the Prophet Muhammad attacked Christians and burned churches on Saturday, killing at least 15 people in the deadliest confrontation yet in the whirlwind of Muslim anger over the drawings.

It was the first major protest to erupt over the issue in Africa’s most populous nation. An Associated Press reporter saw mobs of Muslim protesters swarm through the city center with machetes, sticks and iron rods. One group threw a tire around a man, poured gas on him and set him ablaze.

In Libya, the parliament suspended the interior minister after at least 11 people died when his security forces attacked rioters who torched the Italian consulate in Benghazi.

Right-wing Italian Reforms Minister Roberto Calderoli resigned under pressure, accused of fueling the fury in Benghazi by wearing a T-shirt emblazoned with one of the offending cartoons, first published in September in a Danish newspaper.

In what has become a daily event, tens of thousands of Muslims protested – this time in Britain, Pakistan and Austria – to denounce the perceived insult. But it was in Nigeria, where mutual suspicions between Christians and Muslims have led to thousands of deaths in recent years, that tensions boiled over into sectarian violence.

Thousands of rioters burned 15 churches in Maiduguri in a three-hour rampage before troops and police reinforcements restored order, Nigerian police spokesman Haz Iwendi said. Iwendi said security forces arrested dozens of people in the city about 1,000 miles northeast of the capital, Lagos.

Chima Ezeoke, a Christian Maiduguri resident, said protesters attacked and looted shops owned by minority Christians, most of them with origins in the country’s south.

“Most of the dead were Christians beaten to death on the streets by the rioters,” Ezeoke said. Witnesses said three children and a priest were among those killed.

Nigeria has been spared much of the violence seen elsewhere in the world, though lawmakers in the heavily Muslim state of Kano burned Danish and Norwegian flags and barred Danish companies from bidding on a major construction project. Kano lawmakers also called on the state’s 5 million people to boycott Danish goods.

Nigeria, with a population of more than 130 million, is roughly divided between a predominantly Muslim north and a mainly Christian south.

With Saturday’s deaths, at least 45 people have been killed in protests across the Muslim world, according to a count by The Associated Press.