Islamabad, Pakistan – At about 12:30pm (07:30 GMT) on Tuesday afternoon, Khalid Khan, a 25-year-old lawyer, was waiting for his lunch with his friend, Fawad Khan, at the cafeteria of Islamabad’s District Judicial Complex.

Suddenly, a loud boom shook the cafeteria and the entire judicial complex.

“I first thought that the roof will collapse on me,” Khalid told Al Jazeera outside the complex, two hours later.

The complex had been hit by a suicide attack. According to official figures, at least 12 people were killed and more than 30 were injured, several of them critically, when the bomber blew himself up at the entrance of the court complex.

Prime Minister Shehbaz Sharif blamed “India-backed proxies” operating from Afghanistan for carrying out the attack.

India, where a car explosion on Monday evening killed at least 13 people, said that it “unequivocally” rejects the “baseless and unfounded allegations being made by an obviously delirious Pakistani leadership”.

In a statement issued on Tuesday evening, Randhir Jaiswal, the spokesperson for India’s Ministry of External Affairs, said Islamabad was attempting to “deflect the attention of its own public from the ongoing military-inspired constitutional subversion and power-grab unfolding within the country”, appearing to refer to the 27th constitutional amendment being debated in Pakistan’s National Assembly.

“The international community is well aware of the reality, and will not be misled by Pakistan’s desperate diversionary ploys,” Jaiswal added.

The constitutional amendment has sparked criticism from activists, sitting judges and opposition parties for granting lifelong immunity from criminal prosecution for the country’s senior-most military officers, and for setting up a parallel Federal Constitutional Court, which many fear could undermine the Supreme Court.

But on Tuesday, it was the District Judicial Complex in Islamabad that was shaken, as the impact blast there reverberated across South Asia.

The sound of the explosion was heard in nearby residential areas and office buildings. Soon after, videos of the incident went viral on social media, showing flames and plumes of smoke rising from a charred vehicle near a security barrier at the compound’s entrance.

In other clips, lawyers were seen rushing out to help those on the road as security personnel surrounded the premises.

Witnesses said that at the time of the blast, nearly 2,000 people were inside the complex, including judges, lawyers, litigants and court staff.

They described an explosion so powerful that windows in several courtrooms were shattered, and body parts were strewn across the site, including the head of the suicide bomber.

With different gates for entry and exit, and the main gate closed immediately after the blast, police initially instructed people to stay inside before allowing them to leave about 25 minutes later.

Muhammad Shehzad Butt, a 52-year-old lawyer, was among them. He said he had been heading towards the cafeteria when the explosion occurred.

“It was utter pandemonium, and in the panic, most of the people were trying to exit the complex, causing havoc at the gate, while many others tried to get back inside the building,” he told Al Jazeera outside the complex.

After the attack, authorities cordoned off the area, placing barriers to keep the media from entering or approaching the site where the suicide bomber detonated the explosives.

A large number of journalists gathered outside the compound, hoping to capture visuals, but officials initially denied them access.

By then, most litigants had left, though some lawyers lingered nearby, speaking with reporters and YouTube vloggers recording their accounts.

Butt, the lawyer, said that when he arrived at court in the morning, security checks appeared routine but thorough. However, he heard from colleagues that there was an additional layer of screening that day.

This was corroborated by Khalid, the lawyer from Quetta who has worked in Islamabad for the past five years.

“This morning, when Fawad and I reached the court premises, we had to wait slightly longer as there was extra checking at the entrance. There was no concern, but we just felt that maybe some VIP might be visiting the court or some delegation,” he said.

Despite the dozen people killed, including one lawyer, both Khalid and Fawad, who is originally from Swat, said they felt no fear about returning to work the next day.

“We have seen enough of this [violence],” Khalid said. “These things don’t scare us.”