Five officials of the capital's Counter Terrorism Force were arrested after being booked on Saturday for the murder of a 22-year-old man in Islamabad earlier in the day.

According to the first information report of the incident, registered on the complaint of the deceased's father, Nadeem Younis Satti, at the capital's Ramna police station, Osama received multiple bullet wounds and died on the spot after police opened fire at his car on Kashmir Highway.

Satti said his son's body was shifted to Pakistan Institute of Medical Sciences where it was found he had received one bullet in his head, one in his chest and the others all over his body.

He further claimed that the policemen had shot dead his son "brutally" over a mere exchange of words the previous day after which they had threatened his son. "My son lost his life due to an ordinary exchange of terse words," Satti said in the FIR, adding that his son had told him about the verbal altercation after it had happened.

Police, on the other hand, said the incident was a case of "misunderstanding". Sub-divisional police officer Khalid Awan said police had received reports of a fleeing car after a robbery in Shams colony when Osama's car was also in the area.

"Coincidentally, Osama’s car was also in the vicinity," he said, adding that it seemed suspicious to an anti-terror squad, which at first had motioned the vehicle to stop but opened fire once instructions were not complied with.

"After Islamabad police chief took notice and other senior officials reached the scene, they determined the deceased was innocent and started proceedings following which the squad personnel were taken into custody," he said.

In a statement on Twitter, Islamabad Police termed the episode a "case of firing on suspicious vehicle in Sector G-10". However, it added that the Islamabad IG had taken notice of the incident and formed an investigation committee to probe further. "The officials involved in the incident have been arrested. Action will be taken according to law," it said

Osama had gone out to drop a friend at the National University of Science and Technology (NUST) around 2am on the night between Jan 1 and Jan 2, according to his father, who alleged that the five policemen had followed his son before attacking.

"They forced his car to stop and then in a display of terrorism and barbarity they fired 17 bullets at the car from all four sides," Satti said in the FIR.

The FIR, which was registered under section 7 of the Anti-Terrorism Act, 1997, and sections 302 (premeditated murder), 148 (rioting armed with deadly weapon) and 149 (common intention/object) of the Pakistan Penal Code, identified the shooters as Mudassar Iqbal, Shakeel Ahmed, Muhammad Mustafa, Saeed Ahmed and Iftikhar Ahmed.

All Pakistan Anjuman-e-Tajran (APAT), a traders' body of which Satti is a member, condemned the incident. The president of the APAT, Ajmal Baloch, said the youth's killing was "the worst example of police brutality". He called for immediate arrests of the accused and an inquiry in the high court.

"The trader's son was a student, not a terrorist. The trader community of Islamabad strongly protests this unnecessary killing," said Baloch.

Meanwhile, Islamabad Chief Commissioner Amir Ali Ahmed took notice of the incident and ordered a judicial inquiry, to be conducted by an additional district magistrate, into the police firing of Osama Satti, a statement from his office said.