Elias Naser looked shellshocked standing on the side of the road, a few hundred metres from where the car bomb went off, a bloodstained jacket neatly folded over his arm. “It’s someone else’s blood,” he said, eyeing an entrance to the hospital, waiting for news from his colleague who was admitted with severe injuries.

A suicide bomber had, on Wednesday morning during rush hour, detonated explosives hidden in a sewage tanker on a pickup close to the German embassy in the Wazir Akbar Khan area of the capital.

At least 83 people were killed and at least 461 injured, according to the Afghan ministry of public health. It was one of the deadliest attacks in the Afghan capital since 2001. Hours after the explosion, plumes of smoke still wafted over the diplomatic enclave.

Naser had been at work inside the nearby Azizi Bank when he had felt a deep rumble. It was followed by a blast that shattered everything around him. “First, it felt like an earthquake, then everything came down, windows, the ceiling. The electricity cut out,” he said.

A crater in front of the German embassy in Kabul created by the huge explosion on 31 May. Photograph: Rahmat Gul/AP

The target of the attack, on the fifth day of Ramadan, might have been foreign embassies – the area is home to half a dozen, including the French, and close to the presidential palace.

But outside the fortified security walls, where the car bomb left a crater several metres deep, it is mostly civilians on the crowded streets. Connecting two main traffic circles, the strip is open to pedestrians and vehicles, and is always busy, particularly in the morning.

A few hundred metres away, outside the Italian-run emergency hospital, also damaged in the blast, scores of people lined up anxious to hear from injured relatives and friends. Once in a while, a medic opened the door slightly to shout a name, causing commotion in the crowd.

Wailing women beat their fists against the metal gates, crying the names of loved ones, while guards tried to maintain calm in the chaos. “My colleague is in there,” said one woman, describing how her co-worker had been burned in the face.

Scores of people lined up anxious to hear from injured relatives and friends. Photograph: Sune Engel Rasmussen/The Guardian

At one point, police officers got into a heated scuffle with medical personnel on the other side of the hospital gate, who appeared to be denying them entry with their weapons.

Two hours after the blast, groups of children streamed through the police barricades from the Amani school close to the blast site. Some looked shaken after being kept inside their classrooms for hours. Others held on to anxious parents who had come to fetch them.

The explosion woke up civilians up to a mile away. Across a radius of several hundred metres, shopkeepers were sweeping broken glass off the pavement.

Entezar, a barber, said he was inside his shop when the explosion happened. “At first I didn’t know what smashed my windows. The whole window blew out,” he said, pointing to the shop’s facade.

A driver for the BBC, Mohammad Nazir, and Aziz Navin, a staff member for the ToloNews, an Afghan TV channel, were among those killed. Navin was found after colleagues had searched two hospitals, attempting to identify bodies burned beyond recognition, Lotfullah Najafizada, the director of ToloNews, said on Facebook.

People wounded in the bomb blast in Kabul on 31 May. Photograph: Shah Marai/AFP/Getty

The attack was the latest in a series of extremely powerful explosions in Kabul over the past two years. As foreigners have gradually vacated the streets and receded behind security barriers, the insurgents’ bombs seem to have grown in magnitude. The consequence is that more civilians die.

According to the UN 923 Afghan children were killed in conflict last year, a record high and a 25% increase from 2015. The UN reported the capital having the highest number of civilian casualties, followed by Helmand, Kandahar and Nangarhar.

The Taliban denied responsibility for the attack, though it came as the group was stepping up its annual “spring offensive”. The group was behind a similarly powerful attack in April 2016 on an intelligence headquarters in central Kabul that killed more than 60 people and injured 300.

Self-declared Isis affiliates have also claimed responsibility for several recent bombings in the Afghan capital, including a powerful blast targeting an armoured Nato convoy that killed at least eight and wounded 28 on 3 May.

Isis claimed an attack on a crowd of protesters in Kabul last summer, which killed up to 100 people.

On Wednesday the Afghan interior ministry said eight national army soldiers had died, but the majority of victims were understood to be civilians. An Afghan embassy guard was killed, according to Germany’s foreign minister, Sigmar Gabriel.

Hugo Llorens, the US chargé d’affaires at the US embassy in Kabul, called the attackers “small but despicable and barbaric cults who only know death and destruction” and who had a “nihilistic opposition to the dream of a peaceful future for Afghanistan”.

As evening fell, and people left the streets to break fast, a dozen police officers were left to guard the attack site and keep watch over the destroyed remains of the street.