Travellers gather, stranded at the Lamu jetty, following an attack by Somalia's militant group Al Shabaab. Reuters

A Kenyan government official says four people are dead after a raid by suspected Al Shabab extremists in eastern Garissa County.

Deputy county commissioner Kibet Bowen said on Tuesday the gunmen targeted police officers at a roadblock near the village of Saretho. Police killed two of the suspected extremists, he said.

He said stray bullets killed the residents during the fighting.

The Al Qaeda-linked Al Shabab has vowed retribution on Kenya for deploying its troops in 2011 to fight the extremist group in neighbouring Somalia.

Since December the group has increased attacks inside Kenya including Sunday's attack on a military base that killed three US military personnel.

Associated Press