An explosion at a mosque in the Afghan city of Herat has killed about 30 people and injured dozens more.
The blast, which struck the Jawadia mosque, coincided with evening prayers at around 20:00 local time (15:30 GMT).
Officials said there were at least two attackers - one a suicide bomber, and another who shot at worshippers with a firearm.
A spokesperson for the local governor told the BBC the death toll could rise.
He said at least 29 people had been killed, and another 64 were injured.
Both attackers are dead, a police spokesperson told AFP news agency.
The governor's representative said the suicide attacker also opened fire inside the mosque before detonating his explosives.
Reuters reported grenades were thrown, citing local police.
The state broadcaster in neighbouring Iran, IRIB, said that seven gunmen were involved. The report has yet to be confirmed by local sources in Afghanistan.
No group has said it was behind attack, which occurred in a predominantly Shia Muslim area. A spokesman for the Taliban, which has struck Shia mosques in the country before, condemned the attack in a text message sent to reporters.
Herat, close to the border with Iran, is considered one of Afghanistan's more peaceful cities.
The attack there comes one day after a battle at the Iraqi embassy in the capital, Kabul, which also saw gunmen launch an assault following a suicide explosion. So-called Islamic State (IS) said it had carried out that attack.
Areas dominated by Shia Muslims in Afghanistan have been hit by attacks repeatedly in the past year, by both IS and the Taliban.
Many of the casualties have been civilians, with injury numbers rising for the past five years as attacks increased.
In May, a huge bombing in the centre of Kabul killed more than 150 people, the deadliest militant attack in the country since US-led forces ousted the Taliban from power in 2001. It is not clear what the intended target was.