The security committee said on Saturday that authorities in Kazakhstan held former head of the national security committee, Karim Massimov, on suspicion of treason.
Massimov, who was fired this week as protests raged across the Central Asian country, was arrested along with several other officials, the National Security Committee said in a statement. It didn't say who they were or provide further details.
Dozens of people have died in the past 30 years of independence, and public buildings across Kazakhstan have been attacked and destroyed in the worst violence experienced by the former Soviet republic.
Security forces appeared to have reclaimed the streets of Kazakhstan's main city after several days of violence. The Russian-backed president, Kassym-Jomart Tokayev, said he had ordered his troops to shoot to kill to put down a countrywide uprising.
At Tokayev's invitation, a Russian-led military alliance has been deployed at a time of high tension in East-West relations. Russia and the United States are gearing up for talks on the Ukraine crisis next week.
Massimov is widely viewed as a close ally of former President Nursultan Nazarbayev. He has twice been prime minister and has also served as head of the presidential administration under Nazarbayev.
Nazarbayev, 81, was the longest-serving ruler of an ex-Soviet state until he handed over the presidency to Tokayev in 2019. His family is widely believed to have retained influence in Nur-Sultan, the purpose-built capital that bears his name.