Authorities in Kazakhstan declared a nationwide state of emergency and promised a tough crackdown on Wednesday as mass unrest plunged the country into chaos. Meanwhile, President Kassym-Jomart Tokayev asked for the help of the Russia-led Collective Security Treaty Organization (CSTO).

"These terrorist gangs are international, have undergone serious training abroad, and their attack on Kazakhstan can and should be viewed as an act of aggression," he said in a televised speech.

"Today I appealed to the heads of CSTO states to assist Kazakhstan in overcoming this terrorist threat," he added on state television.

Kazakhstan's armed forces have been called in to restore order and break up the riots about energy prices, Tokayev also said. He also announced that Almaty city's airport, which had reportedly been occupied by protesters the day before, was back under government control.

Long seen as one the most stable of the ex-Soviet republics of Central Asia, energy-rich Kazakhstan was facing its biggest crisis in decades after protesters angry over rising fuel prices stormed government buildings.

Authorities appealed for calm but also shut down the internet and warned that lawlessness would not be tolerated.

President Tokayev accused the protesters of "massive attacks on law enforcement" that left several dead and wounded.

"I intend to act as tough as possible ... Together we will overcome this black period in the history of Kazakhstan," he said.

Protests spread across the nation of 19 million this week in outrage over a New Year increase in prices for liquid petroleum gas (LPG), which is widely used to fuel cars in the west of the country.

Thousands took to the streets in the country's biggest city Almaty and in the western province of Mangystau, saying the price rise was unfair given oil and gas exporter Kazakhstan's vast energy reserves.

After a night of unrest that saw more than 200 people detained, several thousand protesters stormed the mayor's office in Almaty on Wednesday afternoon and appeared to have seized control of the building.

Stun grenades, tear gas

Police fired stun grenades and tear gas at the crowd, some armed with batons and shields seized from police, but were unable to prevent them from entering the building, an Agence France-Presse (AFP) correspondent at the scene said.

Local media said protesters then set their sights on the presidential residence in Almaty. Both it and the mayor's office were reported to be in flames.

There were reports of widespread unrest throughout the country and unconfirmed claims that protesters had seized control of the airport in Almaty.

Several flights from Moscow to cities in Kazakhstan were canceled or postponed on Wednesday night.

But the full picture was unclear after major disruptions to communications, including a nationwide shutdown of the internet, the blocking of online messengers and cuts to mobile phone services.

The protests are the biggest threat so far to the regime established by Kazakhstan's founding president Nursultan Nazarbayev, who stepped down in 2019 and ushered Tokayev into the presidency.

Tokayev tried to head off further unrest by announcing the resignation of the government headed by Prime Minister Askar Mamin early on Wednesday.

He also announced he was taking over from Nazarbayev as head of the powerful security council, a surprise move given the former president's continued influence.

But with protests escalating, the government late on Wednesday said a state of emergency declared in protest-hit areas would be extended nationwide and in effect until Jan. 19.

It imposes an overnight curfew, restricts movements and bans mass gatherings.

The restrictions are aimed at "ensuring public safety, restoring law and order, and protecting rights and freedoms of citizens," a broadcaster said on state television channel Khabar 24.

Much of the anger appeared directed at Nazarbayev, who is 81 and had ruled Kazakhstan since 1989 before handing power to Tokayev.

"Old Man Out!"

Many protesters shouted "Old Man Out!" in reference to Nazarbayev and images posted on social media showed a statue of the ex-president being torn down.

Tokayev was hand-picked as a successor by Nazarbayev, a close ally of Russian President Vladimir Putin.

One of five ex-Soviet nations in Central Asia, Kazakhstan is of crucial importance to Russia as an economic partner and home to a large ethnic Russian population.

Moscow called for a "peaceful solution ... through dialogue, not through street riots and violation of laws."

The European Union and the United Nations called for "restraint" on all sides, while Washington urged authorities to allow protesters to "express themselves peacefully."

Kazakhstan's government tolerates little real opposition and has been accused of silencing independent voices.

Spontaneous, unsanctioned protests are illegal despite a 2020 law that eased some restrictions on freedom of assembly.

Smaller rallies had been staged in cities across the republic from Sunday, beginning with the town of Zhanaozen in Mangystau.

The initial cause of the unrest was a spike in prices for LPG in hydrocarbon-rich Mangystau.

Reports by independent media suggested that Tokayev's announcement of a new price of 50 tenge (11 U.S. cents) per litre, down from 120 at the beginning of the year, failed to weaken the rallies in Zhanaozen and Mangystau's capital Aktau as demonstrators aired new demands.