Attackers have detonated explosives before storming the offices of the Save the Children charity in the eastern Afghan city of Jalalabad.

At least 11 people are reported injured so far.

A suspected suicide car bomb blast began the assault, with the gunmen now said to be using machine guns and RPGs from higher floors in the building.

Images showed residents fleeing from the area. No group has yet said it is behind the attack.

Jalalabad, near the border with Pakistan, is often targeted by Taliban militants but it is also a stronghold for the Islamic State group, whose fighters have been active there since 2015.

The latest attack comes days after Taliban gunmen stormed a luxury hotel in Kabul killing at least 22 people, mostly foreigners.

In a Twitter message the group denied carrying out the Jalalabad attack.

It started at about 09:10 local time (04:40 GMT) on Wednesday when a suicide attacker detonated a car bomb at the entrance to the Save the Children compound, Ataullah Khogyani, a provincial government spokesperson, told the BBC.

An eyewitness who was inside the compound at the time told AFP news agency that he saw a gunman hitting the main gate with a rocket-propelled grenade (RPG).

Images showed a huge plume of thick black smoke rising from the compound.

Local journalist Bilal Sarwary said police had told him Afghan commandos were at the scene and that the attackers were on the upper floors of the building, using heavy machine guns, grenades and RPGs.

He says initial reports suggest there are two or three attackers.

One WhatsApp message, reported by AFP to be from an employee, read: "I can hear two attackers... They are looking for us. Pray for us... Inform the security forces."

An emailed statement from a Save the Children spokesperson said the group was "devastated" at the news of the attack, adding: "Our primary concern is for the safety and security of our staff."

There are several other aid agencies in the area, along with government offices.

Save the Children carries out education, healthcare and protection work for Children in Afghanistan.

Charity groups continue to work under tough conditions in the country, facing regular attacks and kidnappings. The Red Cross announced in October it was drastically reducing its presence in Afghanistan after seven of its staff were killed in attacks in 2017.