One explosion was in a minibus and the second at the Gikomba market in the center of the Kenyan capital of Nairobi. The blasts which killed at least 13 people and injured 70 Friday were caused by grenades, according to the town’s police commander. They followed travel alerts, warning of a high threat of terrorist attacks issued by the US, Australia and Britain, as a result of which hundreds of vacationers were evacuated from Nairobi and Mombasa Thursday. Kenyan authorities called the warnings unfriendly acts. DEBKAfile: The outrage was attributed to the al Qaeda-linked Somali al-Shabaab..