At least 15 people have been killed in the violence between striking workers and police in Zhanaozen, a remote oil town of 90,000 people, authorities said. Witnesses and human-rights workers have said the number of dead could be many times higher.
More than 100 people were reported injured, with many taken to the Caspian Sea city of Aktau 90 miles northwest, due to a shortage of local hospital beds.
As many as 3,000 people protested in Aktau Monday, local news reports cited by The New York Times indicated, and unrest was reported spreading to other cities and towns.
Workers at two other oilfields also went on strike in response to the Zhanaozen violence, officials said.
Reporters visiting the town were not freely permitted to speak with detainees or residents.
In an effort to ease tensions, Kazakh Prime Minister Karim Massimov Monday announced the formation of a government commission to investigate the violence and address the oil workers' grievances, the Russian news agency Interfax reported.
The clashes began Friday after Zhanaozen police opened fire on striking oil workers who had occupied a city square for six months demanding better wages.
They spread Saturday as several hundred protesters blocked and damaged railroad tracks in Shetpe, a town near Aktau, to protest the other activists' treatment.
President Nursultan Nazarbayev Saturday imposed a three-week state of emergency in Zhanaozen, and Interior Minister Kalmukhambet Kasymov said Sunday live firearms would continue to being used to crack down on protesters.
The violence broke out on the 20th anniversary of Kazakhstan's independence from the Soviet Union as Nazarbayev led a celebration in the capital, Astana, with the unveiling of a replica of Paris's Arc de Triumphe.
Kazakhstan is Central Asia's wealthiest country and has aspirations to become one of the world's top five oil exporters by 2020, Britain's Daily Telegraph reported.