More than 60 people were killed in two days near the town of Mpeketoni.
President Uhuru Kenyatta has blamed “local political networks” for the violence, saying members of one ethnic group were targeted.
Most of the dead were ethnic Kikuyus, like the president. Non-Muslims were singled out to be killed.
The BBC he had been told that 12 women whose husbands were not at home during the second attack in the Poromoko district near Mpeketoni were abducted, but this later proved not to be the case.
The Red Cross says that eight people are still unaccounted for after the first attack on Sunday night. It had said 50 people were missing.
Al-Shabab has said it was behind both attacks, in revenge for the presence of Kenyan troops in Somalia and the killing of Muslims.
Kenya sent troops to Somalia in 2011 to help the weak UN-backed government defeat the militants.