Interior Ministry spokesman Najib Danish told after the blast at the Imam Zaman mosque – in the Qala-Najara neighbourhood in north Kabul – gunmen entered and began shooting.
Danish said there were 14 victims overall, without specifying how many among them had died or been wounded.
More explosions and gunfire echoed from the site of the attack, which police official Mohammed Jamil said was still under way.
“We were here, people were waiting for prayers to start, a suicide attacker came and killed the guards and fired on the other guard at the gate and killed him, then entered the mosque,” eyewitness Ghulam Reza told The Associated Press news agency.
Security forces have been unable to advance fearing even greater casualties. Policemen made an attempt to enter the mosque but withdrew after one of the attackers set off an explosion, said police official Mohammad Sadiq Muradi.
Mir Hussain Nasiri, a member of Afghanistan’s Shia clerical council, said the mosque could accommodate up to 1,000 people.
A sprawling cavernous prayer hall dominates the main floor. The second floor is where the women pray. Nasiri said when police initially sought to get into the mosque, the attackers blocked the door leading to the second floor, which he said would mean they are holding the women hostage.
Al Jazeera’s Jennifer Glasse, reporting from Kabul, said police were still trying to clear the mosque. She quoted eyewitnesses as saying the assailants had run out of ammunition and were stabbing worshippers with knives.
Some of the victims included children.
“Police have cordoned off the area and are trying to evacuate the worshippers,” she said. “It was a busy time, in the middle of Friday prayer as the attack took place,” said Glasse.
Islamic State of Iraq and the Levant’s affiliate in Afghanistan claimed responsibility. ISIL-linked Aamaq website said on Friday two of its fighters carried out the assault. It did not give further details.
The attack was the latest by ISIL to hit the Afghan capital. Last month it hit the Iraqi embassy in Kabul and afterward issued a warning to all Shia in Afghanistan, saying its cadres would attack Shia places of worship.
Within days of the embassy attack, ISIL also took responsibility for a suicide assault on a Shia mosque in western Herat province that killed 32 people.
Source: Al Jazeera and agencies