Suicide bombers struck a crowded Sha mosque in Kabul late Thursday, killing four people in the latest in a series of militant attacks to rattle the Afghan capital during the holy month of Ramadan.
At least eight others were wounded when the bombers blew themselves up in the kitchen of Al Zahra mosque after police prevented them from entering the prayer hall packed with worshippers.
The carnage comes at a time Kabul is already on edge following a wave of deadly bombings, which triggered angry public protests calling for the resignation of President Ashraf Ghani's government over spiralling insecurity.
"Terrorist attack on Al Zahra mosque in west of Kabul," ministry spokesman Najib Danish said. "Three civilians and one policeman was killed and eight others were wounded."
No group has so far claimed responsibility for the assault, but minority Shia areas in Kabul have been frequently targeted in the past by Islamic State militants.
The rise of the Islamic State group has raised the spectre of sectarian discord in Afghanistan, something that the Sunni-majority country has largely been spared despite decades of war.
Last year Afghanistan witnessed a wave of attacks on Shias claimed by IS, which considers Shia Muslims apostates.
The attack occurred as worshippers were preparing for an all-night congregation on a night of Ramadan that holds special significance for Shias.
The Taliban, Afghanistan's biggest militant group locked in a fierce rivalry with IS, denied it was behind Thursday's attack, with a spokesman saying they do not attack places of worship.
General John Nicholson, the top US commander in Afghanistan, has pledged to defeat the local IS affiliate this year.
In April the US military dropped its largest non-nuclear bomb ever used on an IS stronghold in eastern Afghanistan, killing dozens of jihadists, but the group still appears to be resilient.
Islamic State fighters this week captured Tora Bora, a mountain cave complex in eastern Afghanistan that was once the hideout of Osama bin Laden, despite pressure on the jihadists from US-led forces.
Kabul has been on edge since a massive truck bomb on May 31 killed more than 150 people and wounded hundreds in the city's fortified diplomatic quarter, the deadliest attack in the Afghan capital since 2001.
Just days later protesters incensed by the bombing clashed with police, prompting authorities to respond with live rounds, which left at least four people dead.
Separately, suicide bombers tore through a row of mourners at the funeral for one of the protesters, killing at least seven more people.
The carnage during the holy fasting month of Ramadan has left the Afghan capital shaken, with anti-government protesters incensed by the violence setting up a sit-in camp close to the May 31 bombing site.