LAGOS (AP) ― Thick black smoke and flames rose from the burning roadblock that cut off a highway linking Nigeria’s mainland to the islands where the oil-rich nation’s wealthy live. The bare-chested young men who live under the bridge said they had had enough.

“This is oligarchy, this is not a democracy!” shouted Danjuma Mohammed, clutching a rock in each hand. “We are no longer afraid of you! We are ready for war!”

A paralyzing strike called by labor unions to protest spiraling gasoline prices drew tens of thousands into the streets Tuesday to denounce government corruption in Nigeria, a multiethnic nation often violently divided by those who have and those who have not.

The anger also fueled violence that pitted Christians against Muslims in Nigeria’s southwest, where five people were killed in attacks on a mosque and Quranic school.

At least six people were wounded in the attacks in Benin City, Nigerian Red Cross spokesman Nwakpa O. Nwakpa said. On Monday, a mob tried and failed to set a mosque ablaze.

The sectarian violence is among worrying signs of possible countrywide unrest in this nation divided into a mostly Christian south and Muslim north. A radical Islamist sect called Boko Haram has begun killing Christians in the nation’s northeast, leading to a call by a prominent Christian leader for worshippers to defend themselves.

The Benin City attack appeared to be a response to those killings.

“It looks like a reprisal from attacks in the north,” Nwakpa said. “They took advantage of protests.”

The nationwide strike, which began Monday, came after President Goodluck Jonathan removed subsidies on Jan. 1 that had kept gasoline prices low. Overnight, prices at the pump more than doubled, from $1.70 per gallon (45 cents per liter) to at least $3.50 per gallon (94 cents per liter). The costs of food and transportation also doubled in a nation where most live on less than $2 a day.

Jonathan insists the move was necessary to save the country an estimated $8 billion a year, which he promises will go toward badly needed road and public projects. However, protesters ― who joined the strike under the slogan of “Occupy Nigeria” ― say the time has come to end government corruption in a nation where military rulers and politicians have stolen billions.

More than 10,000 people gathered Tuesday at a park in Lagos, where protests were mostly peaceful. However, crowds were tense elsewhere in the city of 15 million.

Dr. Tayo Konolafe, a gynecologist, led a group of young protesters, shouting that he would be ready to abandon his career and “hold a gun” to bring change in the country.

“Everybody is angry. A hungry man is an angry man,” Konolafe declared. “What we are passing through in Nigeria is not poverty ― it is penury.”

Whether the government can hold back nationwide unrest remains unclear. Soldiers are deployed now in the country’s restive central region over fears of ethnic and religious violence, in its northeast to fight Boko Haram and in its oil-rich southern delta to stop militancy. Those operations have had mixed success, while critics say the country’s police force is more focused on collecting bribes from civilians than protecting them.

“I will not say it is easy, but we are trying to contain it,” said Moses Onireti, a police spokesman in Oyo state, where a dusk-to-dawn curfew was imposed to try to control violence. “These protesters are everywhere, everywhere.”

Unrest could affect oil production in Nigeria, which produces about 2.4 million barrels of oil a day and is a top crude supplier to the U.S. However, most fields remain unmanned and offshore oil fields provide much of its capacity. Unions representing some oil workers have promised to strike, but it is unclear what effect on production that has had.

The strike has closed Lagos’ busy Apapa Port, cutting off cargo shipments. Businesses remain shuttered, while air carriers canceled more international flights. Organizers say the strike will continue until the government restores the subsidies.

Meanwhile, anger in the street continues unabated. At the Ikoyi Island roadblock, a convoy of police escorting a member of the country’s elite arrived, with officers loudly loading their Kalashnikov rifles in an attempt to drive the protesters away. Officers put out part of the flaming blockade with an extinguisher, then drove off, leaving the protesters behind.

Another convoy of unarmed officers arrived. They pleaded for calm but the protesters instead threw stones as the officers struggled to put out the flames.

“They will kill us and we will kill them!” the protesters shouted.