KARACHI, May 16: Police have failed to make breakthrough in a series of bomb explosions that occurred within a span of one hour at city’s 21 fuel stations early Thursday.

Four people were injured in the blasts occurred at petrol pumps in Nazimabad, Joharabad, SITE, Sharea Faisal, Gulshan-i-Iqbal, etc., from 4am to 5am. They caused minor damage to the property. Nineteen blasts took place at Shell Pakistan’s outlets and two at Caltex Pakistan’s stations, police said.

The bomb disposal squad said the low intensity bombs were locally assembled with 15-minute timer. They were put into dustbins placed beside fuel pumps by motorcyclists, the squad officials said.

“We have not arrested or associated anyone with the investigation so far,” DIG Investigation Fayyaz Leghari told Dawn on Friday night.

He said the police had been investigating the blasts from various angles.

He said nothing could be ruled out; an act of sabotage, a rift between oil transporters and the petroleum company, an act of terrorism by Jihadi or Al Qaeda elements, or some other possibility. “We are investigating from all angles but so far we have not reached a conclusion.”

The DIG said surveillance cameras installed at one of the petrol stations of Shell Pakistan on Sharea Faisal had obtained the film. “Our experts are analyzing the film.

“There were four cameras, three were functional and but the fourth one which could have focused the culprits, was out of order,” he said.

A police spokesman said that according to information gathered from the staff of stations it was suspected that motorcyclists had placed these devices into dustbins.

He said the sketch of a possible suspect was prepared with the help of description provided by one of the staff members of Shell Pakistan. A video film from the security camera was obtained which was being analyzed, he added.

A Shell Pakistan spokesman said measures were taken to ensure safety and security at all facilities.