A blast outside a girls' school in an area of the Afghan capital populated largely by the Shiite Hazara community on Saturday killed more than 30 people and wounded scores including students, officials said.

The explosion rocked the west Kabul district of Dasht-e-Barchi -- a regular target of Sunni Islamist militants -- as residents were out shopping ahead of Eid-al-Fitr next week that marks the end of Ramadan, the Muslim holy month of fasting.

It comes as the US military continues to pull out its last remaining 2,500 troops from the country, despite faltering peace efforts between the Taliban and Afghan government to end a decades-long war.

"Sadly, 25 martyrs and 52 wounded people have been evacuated to hospitals from the site," interior ministry spokesman Tareq Arian told reporters. "The casualties could rise."

Arian's deputy Hamid Roshan told AFP that an investigation had begun into the explosion, adding that casualties included students.

Health ministry spokesman Dastagir Nazari said several ambulances had been rushed to the site and were evacuating the wounded.

"People in the area are angry and have beaten a number of ambulance workers," he told reporters.

No group claimed the attack so far and the Taliban denied they were involved.

Officials have regularly blamed the Taliban for attacks in Kabul, which the insurgents have steadfastly denied. 

The Taliban have denied carrying out attacks in Kabul since February last year, when they signed a deal with the United States that paved the way for peace talks and withdrawal of the remaining US troops.

But the group has clashed in near daily battles in the rugged countryside with Afghan forces even as the US military continues its withdrawal.

The United States was supposed to have pulled all forces out by May 1 under a deal struck with the Taliban last year, but Washington pushed back the date to September 11 -- a move that angered the insurgents.

Despicable act of terrorism

The European Union mission in Afghanistan condemned what it said was an attack targeting a girls' school.

"The horrendous attack... is an despicable act of terrorism," the mission said on Twitter. 

"Targeting primarily students in a girls' school, makes this an attack on the future of Afghanistan. On young people determined to improve their country."

The United Nations Assistance Mission in Afghanistan (UNAMA) expressed its "deep revulsion" at the blast.

The Dasht-e-Barchi neighbourhood has been a regular target of attacks from Sunni Islamist militants.

In May last year a group of gunmen attacked a hospital in the area in a brazen daylight raid that left 25 people killed, including 16 mothers of new-born babies.

The hospital was supported by Doctors Without Borders, the international medical charity, which later pulled out of the project.

No group claimed that attack, but Afghan President Ashraf Ghani blamed the Taliban and the jihadist Islamic State group.

On October 24, a suicide bomber blew himself up at a tuition centre in the same district, killing 18 people including students in an attack that also went unclaimed.