Four Kenyan police officers have been killed after a suspected extremist being held at a police station grabbed a gun and shot at officers.
Police commandos have been deployed to rescue other prisoners and try to end the stand-off, Kenya's police chief Joseph Boinnet said.
"His attempts to escape were thwarted by quick arrival by other officers," Mr Boinnet said.
The station commander was among those killed, West Pokot county commissioner Wilson Wanyanga said.
Kenya has been trying to contain growing extremism influenced by the al Qaida-linked al-Shabab group based in neighbouring Somalia.
The Islamic State group has also emerged as a threat after authorities said Kenyan youngsters were being recruited by the group.