Deadly Riots in Kenya After Muslim Cleric's Killing NAIROBI, Kenya - Deadly riots broke out in the coastal city of Mombasa on Friday morning after a popular but controversial Muslim cleric was fatally shot in what his followers said they believed was an attack by the security services. Four people were confirmed dead and seven injured in the unrest, according to the Kenya Red Cross, and a church was set ablaze. The violence unleashed bubbling religious tensions in the wake of the terrorist attack last month on a shopping mall in Nairobi, the Kenyan capital, which left more than 60 people dead and investigators grasping for answers. The cleric, Sheik Ibrahim Ismail, was killed Thursday night along with three others when their car was sprayed with bullets as they drove along Mombasa's palm-fringed coastal highway. Sheik Ismail's predecessor, Sheik Aboud Rogo Mohammed, a radical cleric, was killed last year in similar circumstances. Sheik Rogo had been linked to the Shabab, the Somali Islamist militant group behind the Nairobi mall attack. By late Friday morning, after prayer services, Muslim youths were pouring out of the mosque where Sheik Ismail preached, throwing together makeshift furniture barricades in the streets, according to local news reports. Security personnel in helmets and protective vests tried to contain the rioting. But demonstrators smashed windows, left tires burning in the street and hurled stones at police officers in running street battles, television footage showed. Black smoke rose from the white Salvation Army church. Footage showed several officers huddled behind a tuk-tuk, seeking cover from rioters, some with red-and-white scarves wrapped around their faces. The situation in the country since the mall attack remains tense. Witnesses have said that one or more of the attackers may have escaped, and fears of a follow-up assault are running high. Muslims, both Somalis from the country's large diaspora and native Kenyans, have been bracing for reprisal attacks. On Friday, the police said no one had been arrested in the killings of the sheik and the others in the car. "Right now, the area is calm," said a Kenyan police spokeswoman in Nairobi, Zipporah Mboroki. We are investigating the cause of the shooting. The Kenyan authorities this week urged calm in the wake of the Nairobi attack, and called particularly for Kenyan Muslims and non-Muslims to stay united. Muslims were among the dead in the attack on the mall, as well as among the rescuers hailed here as heroes. But the attackers allowed some Muslims to leave unharmed, in what may have been in part an attempt to sow dissent. The Shabab has claimed responsibility for the mall attack, but the identities of the attackers have yet to be determined. Followers of Sheik Ismail said they believed that the killings were political, and that his death was the beginning of the feared retribution against Muslims after the mall siege. "The police are killing people while saying it is a war against terrorism; this is a war against Islam," said another radical cleric, Abubaker Shariff Ahmed, according to Agence France-Presse. He called Sheik Ismail's killing an "outright execution." By midday, schools and businesses had shut down in Mombasa, Kenya's second-largest city and most important port. One foreigner working in Mombasa said he was forced to lock himself and 30 of his employees inside their office as violence raged outside. "Everything closed immediately," said the man, who asked not to be identified for fear of reprisal attacks, "because everyone knows what can happen." Muslim youths rioted for three days after Sheik Rogo was killed in August 2012. He was suspected of having links to the bombing of the American Embassies in Kenya and Tanzania in 1998, and was also tied to the Shabab in Somalia. His car was riddled with bullets while he was driving in almost the same place where Sheik Ismail was killed. Nicholas Kulish contributed reporting.