Downtown Bangkok became a flaming battleground Wednesday as an army assault forced anti-government protest leaders to surrender, enraging followers who shot grenades and set fire to landmark buildings, cloaking the skyline in black smoke.

Prime Minister Abhisit Vejjajiva tried Wednesday night to reassure the country that the government would restore calm but fires spread through the capital. His government declared a nighttime curfew, and he said in his televised address troops had been given the go-ahead to shoot at suspected arsonists.

The troops had moved earlier in the day against thousands of so-called Red Shirt protesters, mostly rural poor, who had camped behind barricades in the capital's premier shopping and residential district for weeks, demanding Abhisit call immediate elections.

The army used live ammunition to disperse them, drawing fire from militant Red Shirts. Officials confirmed five protesters and an Italian news photographer were confirmed killed and about 60 wounded.

Witnesses said that six to eight additional dead lay in the temple where hundreds of protesters, including women and children, had sought sanctuary. Mark MacKinnon, a journalist for Canada's Globe and Mail newspaper who was with the refuge seekers, said the situation remained dangerous at Wat Pathum Vanaram, next to the abandoned protest site despite a cease-fire that allowed health workers to evacuate several injured, including a British journalist.

After Red Shirt leaders gave themselves up to police on Wednesday afternoon, rioters set fires at the Stock Exchange, several banks, the headquarters of the Metropolitan Electricity Authority, Central World — one of Asia's biggest shopping malls — and a cinema that burned to ground. There were reports of looting.

Firefighters retreated after protesters shot at them, and thick smoke drifted across the sky of this city of 10 million people.

Sporadic clashes between troops and protesters continued in the night.

The chaos in Bangkok after the two-month protest will deepen the impact on the economy and tourism industry of Thailand, a key U.S. ally and long considered one of the more stable countries in Southeast Asia.

A 10-hour curfew came into force in Bangkok and 23 other provinces at 8 p.m., and the government said army operations would continue through the night in the Thai capital.

It is the first time that Bangkok has been put under curfew since 1992, when the army killed dozens of pro-democracy demonstrators seeking the ouster of a military-backed government.

"Tonight is going to be another worrisome night," government spokesman Panitan Wattanayagorn said.

The government also imposed a partial media blackout on local TV stations, saying all of them will have to air government-prepared bulletins.

"They might be able to show their regular news programs. But we are concerned about their live broadcasts from the scenes," Panitan said.

Protesters had already turned their rage on the local media, which they have accused of pro-government coverage. They attacked the offices of state-run Channel 3, setting fire to cars outside and puncturing water pipes that flooded the building.

"At Channel 3 need urgent help from police, soldiers!!!" tweeted news anchor Patcharasri Benjamasa. "News cars were smashed and they are about to invade the building."

Hours later its building was on fire. Its executives were evacuated by helicopter and police rescued other staff. The English-language Bangkok Post newspaper evacuated its staff after threats from the Red Shirts. A large office building down the street from the Post was set afire.

Thailand's stock exchange would be closed for the rest of the week after rioters set the building's ground floor on fire, its president, Patareeya Benjapolchai, told The Associated Press.

The exchange, where about $600 million of shares change hands each day, may reopen on Monday, she said. The central bank, meanwhile, said all financial institutions in Bangkok including commercial banks would be shut Thursday and Friday.

Unrest also spread to the rural northeast and north of the country, where Red Shirts, who claim Abhisit's government is elitist and oblivious to their plight, retain strong support.

Local media reported protesters set fire to government offices in the city of Udon Thani and vandalized a city hall in Khon Kaen. Udon Thani's governor asked the military to intervene. TV images showed troops retreating after being attacked by mobs in Ubon Ratchathani. There were also reports of fires and unrest in the northern city of Chiang Mai, Thailand's third largest.

Cabinet minister Satit Vongnongteay described the chaos as anticipated "aftershocks."

"There are violence-prone protesters who remain angry," Satit told a news conference.

At least 80 people have been reported killed and nearly 1,800 injured since the Red Shirts descended on Bangkok in mid-March to press their demands. In response, Abhisit offered to hold elections in November, a year earlier than required. Despite initial hopes that could end the standoff, Red Shirt leaders issued new demands and the protesters stayed put.

Many are supporters of populist former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 military coup. Thaksin lives in exile after being sentenced in absentia to two years prison for corruption. The government accuses him of having bankrolled the protests.

The army cranked up pressure last Thursday, trying to blockade the protesters who had camped in the 1-square-mile (3-square-kilometer) Rajprasong district. That military pressure sparked violent clashes. Some 51 of the reported fatalities in the unrest have occurred since then.

The final crackdown began soon after dawn Wednesday, as hundreds of troops armed with M-16s converged on Rajprasong, where high-end malls and hotels have been shuttered for weeks.

Armored vehicles crashed through barricades of piled tires and bamboo stakes, then soldiers gradually moved toward the protesters' hub, opening fire and drawing return fire from militant Red Shirts, Associated Press journalists saw.

Bullets flew overhead and several grenades exploded near the soldiers, forcing them to pull back and take cover briefly before pushing forward. A Canadian freelance reporter was injured by grenade shrapnel. Two other journalists were wounded earlier, one Dutch man and an American documentary filmmaker.

With no hope of resisting the military's advance, seven top Red Shirt leaders turned themselves in on Wednesday afternoon, saying they cannot see their supporters being killed.

"Brothers and sisters, I'm sorry I cannot see you off the way I welcomed you all when you arrived here. But please be assured that our hearts will always be with you," Nattawut Saikua, a key leader, said as he was being arrested.

"Please return home," he said.

By mid-afternoon, the army announced it had gained control of the protest zone and the operations had ended — nine hours after troops launched the pre-dawn assault, although sporadic clashes with rioters continued into the night.