Kenya's police chief is asking residents to be "extra vigilant" of attacks in the week following Sunday's anniversary of the Westgate Mall attack.

David Kimaiyo said Saturday police have doubled patrols across the country and asked entertainment facilities to continuously review and update security arrangements.

Al-Shabab militants from Somalia claimed responsibility for the Sept. 21 Westgate Mall attack that left 67 people dead.

One person died and 13 others wounded Thursday in separate gun and grenade attacks in the towns of Wajir and Garissa.

Thursday's attacks are among a wave of violence in Kenya blamed on al-Shabab. The gun and grenade attacks started in October 2011 when Kenya sent its troops to Somalia to fight the militants. Al-Shabab has vowed retribution for Kenyan troop presence in Somalia.