Rioting youth in Kenya’s second largest city of Mombasa surprised the police on a second day of clashes on Tuesday with a grenade attack that reportedly killed two people and injured 16 others, reports say.

One of those killed was a police officer.

The clashes which started on Monday over the killing of radical preacher, Aboud Rogo Mohammed, took a new turn with the stone-throwing youth hurling a grenade at the police.

Mr. Rogo, who the US accused of backing Islamist fighters in Somalia, was killed in a drive-by shooting, the BBC reports.

Police fired tear gas and warning shots on Tuesday, as youth barricaded streets with burning tyres in the predominantly Muslim community of Majengo.

Mobs moved around Mombasa’s city centre, taunting police who arrested some of the protesters.

The violence started after armed men sprayed Mr. Mohamed’s car with bullets on Monday, in an attack many Muslims in Mombasa blamed on the police. The police have denied the claim.

Mr. Mohammed was the spiritual leader of the Muslim Youth Centre (MYC).

Kenya’s Prime Minister, Raila Odinga, has appealed for calm, saying the country should avoid an “inter-religious war”.

“Let’s act with restraint as law enforcement agencies get to the root of the matter,” he is quoted by the BBC as saying. “We urge Muslims and Christians not to fight.”

One person was killed and churches were attacked in clashes on Monday.

A senior police intelligence officer in Mombasa, Benedict Kigen, announced Tuesday’s grenade attack.

“They have attacked our officers…. Two people are dead, one of them is an officer, the other is a civilian,” Reuters news agency quotes him as saying.

Sixteen policemen were wounded in the attack, Kenya’s Daily Nation newspaper reports.

Somalia’s militant Islamist group al-Shabab condemned Mr. Rogo’s killing and said Muslims in Kenya should boycott next year’s presidential election.