Tensions are running high in the northern Nigerian city of Kano after thousands of protesters converged on the state governor's office, prompting police to push them back by firing tear gas and shooting live ammunition into the air.
Protesters on Monday also set two vans ablaze and tried to torch the home of the central bank chief, Lamido Sanusi, but police stopped them.
The office of the secretary of the state government, its highest administrative officer, was also set on fire, causing serious damage.
A Red Cross official said that at least 30 people were injured in the clashes, including 18 with bullet wounds. A hospital source said later that two of those shot had died.
The state government imposed a nighttime curfew on the city and it was unclear whether authorities would disperse thousands of protesters who remained at the city's main square.
In and around Lagos, the country's largest city, demonstrations mostly remained peaceful except for one reported incident of police gunfire that killed a demonstrator, according to witnesses and hospital sources.
Bonfires made of tyres burned along main roads as protesters marched past, with an estimated 10,000 or more converging at a designated location for a rally.
Protest leaders in Lagos were keen to avoid provoking police after authorities were accused of using excessive force against demonstrators last week and shooting dead one person.
The strike comes after the government's controversial move to end fuel subsidies on January 1, which caused petrol prices to more than double in the continent's most populous nation.
Transport costs have followed suit, sharply increasing the price of commuting in a country where most of the 160 million people live on less than $2 per day despite its oil wealth.
Al Jazeera's Haru Mutasa, reporting from Abuja, the Nigerian capital, said protesters had vowed to continue demonstrating on Tuesday.
|Ngozi Okonjo-Iweala, the Nigerian finance minister, speaks to Al Jazeera from Abuja
"They've gone home and they said they'll return tomorrow morning," she said.
"Most of the protesters are saying that they plan to be peaceful - but they are very angry, saying that the price of bread has doubled."
"Some people fear that in a few days, if it continues of course, they could see shortages of food."
Much of the country has been united in anger against the move despite a strong push from President Goodluck Jonathan and his economic team to make their case for why fuel subsidies had to be abandoned.
Protests against the decision to end fuel subsidies last week became increasingly volatile, with police firing tear gas and accused of using excessive force to disperse demonstrators.
A union also accused police of shooting dead a demonstrator last week, but authorities denied the charge, saying he was killed by a mob.
The country's House of Representatives held an emergency session on Sunday and approved a measure calling on the government to reinstate fuel subsidies to allow for further consultations on the issue.
There was, however, no sign the government would back down.
Jonathan sought to win support for the government's move in an address on national television on Saturday night, but unions rejected it.
He pledged to reduce salaries for political office holders in the executive branch by 25 per cent as well as to improve public transport, including rail lines, among other areas.
"To save Nigeria, we must all be prepared to make sacrifices," he said.
Economists say removing fuel subsidies is vital for the country to improve its woefully inadequate infrastructure and ease pressure on its foreign reserves.
The government says it spent more than $8bn on subsidies in 2011.
Many Nigerians view the subsidies as their only benefit from the nation's oil wealth, and lack any real trust in government after years of deeply rooted corruption.