Five suspected militants were killed in gunbattles with police that followed a series of recent armed attacks that have challenged stability of the energy-rich ex-Soviet nation, authorities said Friday, June 10, the Associated Press reports.

Kazakhstan's National Security Committee said its agents tracked down four suspects hiding in an apartment building early Friday in Aktobe, a city in Kazakhstan's northwest, about 70 kilometers south of the Russian border.

The agency said the suspects refused to surrender, fired on police and security officers, and were killed in the ensuing gunbattle.

Another gunman fired at police at a different location and was killed by retaliatory fire. Two police officers were wounded, the committee said, according to AP.

At least 20 people were killed in Aktobe on Sunday when groups of gunmen attacked a military base and gun shops. The death toll included three servicemen, four civilians and 13 attackers. Nearly 40 people were wounded.

Kazakhstan's authorities described the violence as a terror attack and blamed it on religious extremists. Police and security forces have launched a sweeping hunt for those involved in the attacks.