Media playback is unsupported on your device Media caption Security forces deploy to the site of the attack

More than 20 people have been killed and 40 injured in an attack on a Shia mosque in the Afghan capital, Kabul, officials say.

A suicide bomber detonated explosives at the mosque's gate before two gunmen entered as worshippers gathered for afternoon prayers.

Afghan special forces fought a four-hour gun battle with the attackers and say the gunmen are now dead.

So-called Islamic State (IS) said it was behind the attack.

The group's news outlet, Amaq, said militants had carried out a "commando" attack on the mosque.

Children and police officers are among the victims of Friday's attack, interior ministry officials say.

Last month, dozens of people were killed when a car bomb struck a bus carrying government employees in the capital. The Taliban said they were behind that attack.