At least one person was confirmed dead and ten others seriously injured in an early Sunday grenade attack at a church in Nairobi’s Ngara residential estate, police confirmed. Nairobi deputy regional police chief Moses Ombati and Director of Criminal Investigations Department (CID) Ndegwa Muhoro said the assailant had gone to the God’s House of Miracles International Church pretending to be a worshiper when he lobbed a grenade at other worshipers. "The other worshipers say he had come and surveyed the church before he stood few meters away and hurled the explosive injuring those who were praying. So far we can confirm one death,” Ombati told journalists at the scene of the incident. The deputy police chief said investigations have been launched to establish the motive behind the grenade attacks, the third incident to hit Nairobi this year. "We have launched investigations to establish the motive behind the grenade attacks. We have also launched a major manhunt for the suspects who are still at large,” Ombati said. Ombati said the Sunday incident occurred at around 8:50 a.m. local time (0550GMT) and the injured have been rushed to the local hospitals for treatment. According to the police, the person hurled the grenade when part of the congregation had moved to the front of the church for prayers. The attack comes barely a week after the US embassy warned of an imminent terrorist attack in Kenya is possible. The warning comes as the country’s security forces have been on high alert across the country especially in northern Kenya over an imminent suicide bombing attack by members of the Al-Shabaab group from neighbouring Somalia. However, some faithful said the land on which the church stands has been under a protracted dispute between the church and some locals, a situation they said may have led to the attack which was meant to scare away worshippers. This could not however been confirmed by other worshippers and the police who said the ongoing investigations would reveal those details. Kenya’s Defence Forces (KDF) crossed into Somalia in October last year to flush out Al-Shabaab militants, who it blamed for abducting tourists and threatening her economy. Al-Shabaab militants vowed to attack Nairobi in retaliation after the east African nation which hosted protracted negotiations that culminated in the signing of the federal charter for Somalia in 2005, invaded Somalia to flush out the insurgents it blamed for kidnappings of tourists.More than 30 people have been killed in Kenya mostly in northern region blamed on Al-Shabaab who have since joined Al- Qaida network to cause terror attacks in East African nation.The Kenyan police have particularly warned against the laxity in the screening of cars for explosives at all shopping malls and any business or social gatherings with at least 10 people at any given moment that these might be vulnerable to attacks. Police still insist security has been stepped up and appealed to city residents to be extra vigilant and take security measures seriously, regardless of their status in society.