Russia sent paratroopers into Kazakhstan on Thursday to quell a countrywide uprising after deadly violence spread across the tightly controlled former Soviet state.

Police said they had killed dozens of rioters in the main city Almaty. State television said 13 members of the security forces had died, including two who had been decapitated.

Reuters journalists in Almaty said a presidential residence and the mayor's office were both ablaze. By Thursday afternoon, the city's airport...