People hold wooden crosses, symbolising the people killed by gunmen at Garissa University College, as they pray during a memorial vigil at the "Freedom Corner" in Kenya's capital Nairobi April 7, 2015. Kenyan university students marched in the capital on Tuesday to demand more security from the government after gunmen killed nearly 150 people at a campus in the eastern town of Garissa last week. A citizens group planned to hold a vigil in Nairobi's main park later in the evening, tapping growing public frustration over security in the wake of the attack claimed by al Shabaab Islamists based in neighbouring Somalia. REUTERS/Goran Tomasevic