Kano, Nigeria (CNN) -- At least 15 people were killed Monday in a suicide attack on a Shiite religious ceremony in the northeast Nigerian town of Potiskum and six others in a shooting by soldiers, a Shiite cleric and a paramedic said. A suicide bomber blew himself up amid a large crowd of Shiite Muslims holding the annual Ashura ceremony to commemorate the murder of Imam Husseyn, the grandson of the Prophet Mohammed, in Karbala 1,300 years ago. No one has claimed responsibility for the attack, but militants from the Boko Haram Islamist group, who have waged an insurgency in the region for five years, have been responsible for previous attacks in Nigeria. Soldiers who deployed after the blast, in the Tsohuwar Unguwa area of the town, broke into the nearby Shiite seminary and opened fire on mourners who were sheltering from the blast, killing six, said Mustapha Lawan Nasidi, leader of the Shiites in Potiskum. "A suicide bomber â€Ždetonated explosives he was carrying among a large crowd of people commemorating Ashura near our seminary, Madrasatul Fudiyya, killing 15 people and injuring more than 50 others," Nasidi said. "To our shock, soldiers who deployed to the scene shortly after the blast broke into the seminary, where some people had taken shelter, and opened fire on them, killing six and injuring four others," he said. CNN has asked the Nigerian military for comment on the shooting claim but has not received a response. He said the death toll could grow because of the seriousness of the injuries. "It was a huge crowd, and many of them were affected by the explosion," said a policeman who helped evacuate casualties. Tanimu Musa, a paramedic who attended to the â€Žinjured, called for aid. "We have 21 dead bodies and dozens of wounded. We need more blood and medical supplies to tend to those injured," Musa said. This is not the first deadly attack in Potiskum, the commercial hub of Yobe state. In July, four Shiites were killed in an explosion at an open-air mosque in the Dogo Tebo area of town. And in May 2013, three Shiite worshippers were killed and several injured when gunmen fired on people saying their evening prayers outside Nasidi's home. Both attacks were blamed on Boko Haram. Boko Haram leader denies ceasefire deal .
A bomber killed at least 15 people in an attack on a religious ceremony, a Shiite cleric says .
After the blast, soldiers shot and killed six people who'd sought refuge, the cleric says .
No one claimed responsibility, but Boko Haram has made attacks in the area before .
The Nigerian military has not responded to a CNN request for comment on the shooting claim .
Kano, Nigeria (CNN) -- At least 15 people were killed Monday in a suicide attack on a Shiite religious ceremony in the northeast Nigerian town of Potiskum and six others in a shooting by soldiers, a Shiite cleric and a paramedic said. A suicide bomber blew himself up amid a large crowd of Shiite Muslims holding the annual Ashura ceremony to commemorate the murder of Imam Husseyn, the grandson of the Prophet Mohammed, in Karbala 1,300 years ago. No one has claimed responsibility for the attack, but militants from the Boko Haram Islamist group, who have waged an insurgency in the region for five years, have been responsible for previous attacks in Nigeria. Soldiers who deployed after the blast, in the Tsohuwar Unguwa area of the town, broke into the nearby Shiite seminary and opened fire on mourners who were sheltering from the blast, killing six, said Mustapha Lawan Nasidi, leader of the Shiites in Potiskum. "A suicide bomber â€Ždetonated explosives he was carrying among a large crowd of people commemorating Ashura near our seminary, Madrasatul Fudiyya, killing 15 people and injuring more than 50 others," Nasidi said. "To our shock, soldiers who deployed to the scene shortly after the blast broke into the seminary, where some people had taken shelter, and opened fire on them, killing six and injuring four others," he said. CNN has asked the Nigerian military for comment on the shooting claim but has not received a response. He said the death toll could grow because of the seriousness of the injuries. "It was a huge crowd, and many of them were affected by the explosion," said a policeman who helped evacuate casualties. Tanimu Musa, a paramedic who attended to the â€Žinjured, called for aid. "We have 21 dead bodies and dozens of wounded. We need more blood and medical supplies to tend to those injured," Musa said. This is not the first deadly attack in Potiskum, the commercial hub of Yobe state. In July, four Shiites were killed in an explosion at an open-air mosque in the Dogo Tebo area of town. And in May 2013, three Shiite worshippers were killed and several injured when gunmen fired on people saying their evening prayers outside Nasidi's home. Both attacks were blamed on Boko Haram. Boko Haram leader denies ceasefire deal .
Kano, Nigeria (CNN) -- At least 15 people were killed Monday in a suicide attack on a Shiite religious ceremony in the northeast Nigerian town soldiers, a Shiite cleric and a paramedic said. A Karbala 1,300 years ago. No one has claimed military for comment on the shooting claim but Shiites were killed in an explosion at an Haram. Boko Haram leader denies ceasefire deal .