Deadly riots broke out in Kenya’s main port of Mombasa on Monday after the assassination of a radical cleric linked to Somalia’s Al-Qaeda-allied Shebab militants.At least one person was hacked to death as thousands of angry protestors took to the streets after Aboud Rogo Mohammed -- who was on US and UN sanction lists for allegedly supporting the Shebab – was shot dead."A car behind us aimed at my husband, they shot him on the right side,” said his widow Haniya Said, screaming in grief after the killing by unknown attackers."One person has been killed, he was slashed to death during the protests,” said regional police chief Aggrey Adoli.Cars were set on fire and two churches were looted in the city -- Kenya’s main port and a key tourist hub -- according to an AFP reporter."There is chaos in town now, and our officers are on the ground dispersing the rioters to maintain peace,” added Adoli. "They are demonstrating against the killing of Aboud Rogo, who was shot by unknown people.”Witnesses said that Mohammed’s car was riddled with bullets, and a photograph released by his supporters showed his bloody corpse slumped behind the wheel of a car."He died as we rushed him to hospital. Why have they killed my dear husband?” his widow added, before she and her children were taken to the hospital.Mohammed was placed on a US sanctions list in July for "engaging in acts that directly or indirectly threaten the peace, security or stability of Somalia”, specifically for recruiting and fundraising for the hardline Shebab.The United Nations Security Council placed a travel ban and asset freeze on the cleric in July, saying he had provided "financial, material, logistical or technical support to Al-Shebab”.He was the "main ideological leader” of Kenya’s Al Hijra group, also known as the Muslim Youth Center (MYC), the UN said. The group is viewed as a close ally of the Shebab in Kenya.Mohammed "used the extremist group as a pathway for radicalisation and recruitment of principally Swahili-speaking Africans for carrying out violent militant activity in Somalia”, the UN said.MYC leader Sheikh Ahmad Iman Ali, in a message posted on Twitter, said: "We are on the right track when our leaders get shahadah (martyrdom).”"He will remain in our hearts forever,” the MYC added, while another message offered the grim warning that the "kuffar (infidels) will pay” for his death."The whole city is on fire, there are looters in the streets, cars have been damaged, some have been burnt,” said Francis Auma, from the local organisation Muslims for Human Rights."An imam in the mosque shouted through the speaker ‘blood for blood’, and immediately youths started stoning cars,” said witness Dennis Odhiambo, whose car was damaged and who was forced to flee into a police station for safety.The local Muslim Human Rights Forum condemned Mohammed’s assassination, claiming it "mirrors” the recent killings or disappearance of others "on the country’s terrorism watch list”.Mohammed "repeatedly called for the violent rejection of the Somali peace process”, the US Treasury said, noting he had often advocated the use of violence against both the UN and the African Union force battling the Shebab in Somalia.He "urged his audiences to travel to Somalia to join Al-Shebab’s fight against the Kenyan government”, the Treasury added.Kenyan police arrested the preacher in January, seizing firearms, ammunition and detonators, but later released him on bail.He was previously acquitted of the 2002 bombing of an Israeli-owned hotel near Mombasa which killed 15 people -- 12 Kenyans and three Israelis -- as well as three suicide bombers.The cleric is also alleged to have introduced Fazul Abdullah Mohammed -- the late head of Al-Qaeda’s east Africa cell, shot dead last year in Somalia’s war-torn capital Mogadishu -- to at least one of the men who helped him carry out the twin US embassy bombings in 1998.