At least three people were injured in a grenade attack on Sunday evening in Nairobi\'s Eastleigh residential estate largely inhabited by Kenyans of Somali origin. Regional police commander, Benson Kibui confirmed the incident which took place at around 8:30 p.m. local time at California area in Nairobi, just an hour after another blast went off in Mombasa, injuring seven people. \"There is a vehicle which passed there whose occupants threw grenade at passersby. There are three people who have been slightly injured and have been rushed to the hospital,\" Kibui told Xinhua by telephone. He said bomb experts have been dispatched to scene to ascertain the type of the device which was used in the Nairobi explosion. No arrest has been made but the regional police commander said a major manhunt has been launched to arrest those behind the incident. Eastleigh has been the scene of frequent terror attacks but the police have warned residents and travelers to be extra vigilant and volunteer any information that may assist in the investigations. Kenyan officials have expressed concern in the past that the frequent terrorist attacks in the Eastleigh area were damaging the image of the country and destroying the tourism industry and tasked the team to find out the cause of the terror attacks and come up with immediate solutions to address the situation. Kenya has been blaming Somalia\'s Al-Qaida-linked Al-Shabaab militants and their sympathizers residing in the country for a spate of attacks in Kenya in recent years especially in Nairobi, Mombasa and northern regions. However, the insurgents have not publicly claimed responsibly for the Sunday\'s grenade attacks in Nairobi and Mombasa which has left some 10 people injured.