New Delhi, Oct 15 : More than 30 people have died while 90 others have been injured after an explosion tore through a Shia mosque during Friday prayers in the Afghan city of Kandahar, the BBC reported. Pictures from inside the Bibi Fatima mosque show shattered windows and bodies lying on the ground with some other worshippers trying to help. The explosion's cause is not yet clear, but it is suspected to be a case of suicide bombing. Witnesses said that there were three blasts in the mosque. IS-K, a local branch of the Islamic State, is expected to claim responsibility for the attack, the BBC reported. Kandahar is Afghanistan's second largest city and the spiritual birthplace of the Taliban, so an attack in the city by IS-K, which is extremely hostile towards the Taliban, would be significant. Last Friday, a suicide attack on another Shia mosque during Friday prayers in the northern city of Kunduz had killed at least 50 people. IS-K had said that it carried out the attack, which was the deadliest since the US forces left Afghanistan at the end of August. IS-K, a Sunni Muslim group, is the most extreme and violent of all the jihadi militant groups in Afghanistan. Sunni Muslim extremists have targeted Shia Muslims, whom they see as heretics. IS-K has targeted Afghan security forces, politicians and ministries, the Taliban, religious minorities, including Shia Muslims and Sikhs, US and Nato forces, and international agencies, including aid organisations, the report said. /IANS