Suspected Al-Shabaab militants attacked a police post in Garissa on Tuesday, county police boss David Kerina said.
The militants attacked Hamey Police Post which is located near the Kenya-Somalia border at 2am.
They raided the post from different corners and had a heavy exchange of fire with officers based at the station.
Mr Kerina said an Administration Police officer remained unaccounted for on Tuesday afternoon following the attack.
He added that four officers sustained minor injuries and are out of danger.
"Four officers only got bruises. They fought hard and repulse the enemies," he said.
The police boss said search is underway for the missing officer.
According to a police source, the officers at the station had prior intelligence of an impending attack and were ready to fight back.
The Somali-based militants have in the recent past staged attacks targeting security officials in areas around the Kenya-Somalia border.
On Thursday last week, five police officers were injured when suspected Al-Shabab militants planted Improvise Explosive Devices on the road.
In the same week, four police officers were injured when they were ambushed by suspected militants in Garissa's Ijara Sub-County.