A man was injured when a fire erupted at Customs intelligence office on Quetta's Airport Road on Sunday, the city's senior superintendent of police (operations), Abdul Haq Imrani, said.

The SSP was speaking to the media following a visit to the site after the fire, which erupted reportedly after an explosion.

While there were reports that the fire was caused from an explosion, SSP Imrani did not confirm it and told reporters that no trace of a blast had been found so far.

He added that relevant authorities were carrying out investigations to determine the cause of the fire.

"The security guard will be questioned," he said, adding that firefighters had reached the site soon after the incident and doused the fire after an hour.

The SSP said the man injured in the incident was taken to Civil Hospital, Quetta.

According to police, all items — including records and files — at the office had been reduced to ash as a result of the fire.

Separately, security guard Sanaullah, who was deployed at the office when the incident occurred, said three armed men had barged into the office and held staff members hostage before an "explosion and the subsequent fire".

"They tied [the staff members'] hands and tortured them," Sanaullah said, adding that an "explosion" took place as soon as the armed men left the office, following which a fire erupted.