Witnesses described scenes of panic, confusion and destruction following a devastating bomb blast in Kabul's diplomatic quarter that killed scores of people and wounded hundreds.

"[I have] not heard something this big before", Fatima Faizi, a Kabul resident, told Al Jazeera, minutes after the blast on Wednesday.

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At the Wazir Akhbar Khan hospital, there were scenes of chaos as ambulances brought in wounded and frantic relatives scanned casualty lists and questioned hospital staff for news.

"I couldn't think clearly, there was a mess everywhere," Nabib Ahmad, who was lightly hurt, told the Reuters news agency.

A suspected truck bomb ripped through the heart of Kabul's diplomatic area in an "earthquake-like" blast described by officials as "one of the biggest" to have hit the city. At least 80 people were killed and more than 300 wounded.

Kabul residents said the explosion was so powerful it could be felt throughout the Afghan capital.

"I was just 500m from the location of the explosion, and it was so heavy that in every part of Kabul, people thought as if it was next to them," Mushtaq Rahim, an independent analyst and security commentator, told Al Jazeera.

"It was pretty strong. It felt like a tremor, like an earthquake in many parts of the city. As soon as the blast went off, one could see a huge amount of smoke coming from the area," Rahim added.

Mohammad Hassan, who worked at a bank near the site of the blast, also said the explosion felt "like an earthquake". He suffered a head wound.

The explosion went off at rush hour near Zanbaq Square in Kabul's 10th district, close to shops and restaurants as well as government offices and foreign embassies.

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Faizi said the explosion "was so loud that it shattered" all the windows in her home.

Video from the scene showed debris burning near destroyed buildings and cars.

Gul Rahim, who was at the site, said: "there are a large number of casualties".

Naser Shahalemi, who works in a building about five to 10 minutes from the blast scene, said he felt "a huge gust of wind ... followed by an immediate explosion".

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There was no immediate claim of responsibility for the attack. Zabihullah Mujahid, a spokesman for the Taliban, told Al Jazeera that the group was not responsible for the blast.

Officials have said the death toll is expected to rise. The victims appear mainly to have been Afghan civilians, and there were no immediate reports of casualties among foreign embassy staff.

Shahalemi said that the area where the explosion took place was a "very fast-paced area" and "everything could have possibly been a target".

Embassies damaged

Al Jazeera's Qais Azimy, reporting from Kabul, said the location of the attack was very significant, as it hit one of the Afghan capital's busiest and most secure parts.

"Kabul has been very quiet for the past week, but police have confirmed to us that this was one of the biggest blasts Kabul has ever seen," he said.

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Officials of several embassies in the area, including the German, Japanese, French, Canadian and Bulgarian missions, reported damage to their buildings.

"We are all safe, all our staff, all our personnel are safe. However, the blast was very large and nearby buildings including our own building have considerable damage in terms of broken glass and shattered windows and blown doors, etc." Manpreet Vohra, India's envoy to Afghanistan, told the Times Now television channel.

Emergency, an Italian NGO that operates in a hospital near the site of the blast, wrote on Twitter that the explosion "was so big that our hospital got damaged".

It added its "staff is well and working to treat the wounded arriving from the blast".