Nairobi (AFP) - Kenya on Sunday marks a year since Somali Islamist gunmen attacked Nairobi's Westgate shopping mall, with anniversary commemorations including the unveiling of a memorial stone and candlelight vigil. At least 67 people were killed and scores more wounded when a small group of Al-Qaeda-affiliated fighters walked into the upmarket mall, tossing grenades and executing shoppers and staff.Kenya has been on high alert ahead of the anniversary, especially amid fears of retaliatory Shebab attacks after their reclusive leader and the alleged mastermind of the Westgate attack, Ahmed Abdi Godane, was killed at the start of this month in a US air strike.Police chief David Kimaiyo announced Saturday they are on high alert following fears of a terror attack during the Westgate anniversary."We are prepared in case of anything.