Three people have been killed in a suspected Al-Shabaab attack targeting a bus on Thursday at Nyongoro area, Lamu County.
Three others were also injured in the attack.
Lamu County Commissioner Irungu Macharia confirmed the incident.
The bus had come from Mombasa and was headed to Lamu.
Transport along the Lamu-Garsen road has been suspended as security agencies, including the army, comb the area.
The Somalia-based terror group has ramped up attacks in recent months, with its deadliest being a car bomb that claimed the lives of 79 people in Mogadishu on Saturday.
Al-Shabaab for the first time apologised to civilian victims of the attack.
In Kenya, at least ten people were killed, including police officers, when the terrorists attacked a bus using an Improved Explosive Device (IED) in Kotulo area a week ago.
Its militants also kidnapped two businessmen on December 26 in Liboi area along the Kenya-Somalia border. They were then freed on December 27, with police saying they had launched a manhunt for the culprits after the attack.