According to Uzbekistan's President Shavkat Mirziyoyev, the public protests in the province of Karakalpakstan have resulted in casualties among the civilian population and the security forces.
Rioters carried out "destructive actions" in the town of Nukus, throwing stones, setting fires and attacking the police, according to a statement by Mirziyoyev released on Sunday.
"Unfortunately, there are civilian casualties and law enforcement officials," he said.
Only on Saturday did Mirziyoyev drop plans to take back the province's autonomy after protests, which he said began on Friday.
A local official told an Internet news site that thousands of people had been injured and were in hospital.
According to the opposition politician in exile Pulat Ahunov, at least five people lost their lives.
There are also unconfirmed reports of dozens more dead.
Uzbekistan is a tightly controlled Central Asian state and a former Soviet republic where the government cracks down on any form of criticism.
Human rights organizations denounce police violence.
"There have been unconfirmed reports of excessive use of force by security forces during the July 1 protests in Nukus," Human Rights Watch Europe and Central Asia director Hugh Williamson wrote on Twitter.
He called for an investigation into what was happening.
The Foreign Ministry of neighboring Kazakhstan, whose government had violent protests put down in early January, expressed concern about the events in Uzbekistan.
"We welcome and support the Uzbek leadership's decisions to stabilize the situation in Karakalpakstan," the ministry said in a statement.