The presidential residence in Kazakhstan's largest city Almaty was engulfed in flames on Wednesday and armed protesters stormed another government building, according to news reports, as demonstrations sparked by a rise in fuel prices escalated sharply.
In response to the protests in cities across the country, the government resigned and the president vowed to take harsh measures to quell the unrest.
Late in the day, Kazakh news sites became inaccessible, and the global watchdog organization Netblocks said the country was experiencing a pervasive internet blackout.
But Russia's Tass news agency reported from Kazakhstan that the presidential residence in Almaty, where thousands of demonstrators had gathered outside, was on fire and that the city's main administration building that includes the mayor's office was burning from top to bottom hours after demonstrators broke in.
The protests began Sunday in Zhanaozen, a city in the west where resentment of the government was strong in the wake of a 2011 oil-worker strike in which police fatally shot at least 15 people.
They spread across the country in the following days and on Tuesday large demonstrations broke out in the capital, Nur-Sultan, and in Almaty, the country's largest city and former capital.
Although the protests began over a near-doubling of prices for liquefied gas that is widely used as vehicle fuel, the size and rapid spread of the unrest suggest they reflect wider discontent in the country that has been under the rule of the same party since independence from the Soviet Union in 1991.
In a televised statement to the nation on Wednesday, President Kassym-Jomart Tokayev said authorities intended to act against "law-breakers" with "maximum severity".
Tokayev said police officers had died in clashes with demonstrators, but there were no immediate casualty figures for police or civilians.
In the statement, he also promised to make political reforms and announced that he was assuming the leadership of the national Security Council.
At the start of the year, prices for liquefied gas roughly doubled as the government moved away from price controls.
Although Kazakhstan has extensive gas and oil reserves and mineral wealth, discontent over poor living conditions is strong in some parts of the country.
Many Kazakhs also chafe at the dominance of the ruling party, which holds more than 80% of the seats in parliament.
Additional reporting by The Associated Press.