Explosives experts are piecing together minute bits of debris collected from the van which blew up on Wednesday morning in a busy Ħamrun street.

Sources said it was too early to determine what sort of bomb it was. However, despite the fact that it devastated the red Fiat Fiorino it was in and damaged nearby property as far as 70 metres away, the sources said the capacity of the bomb was not extraordinary.

Explosives experts also pointed to the fact that there was no significant burning in the van, indicating that it might have been TNT or dynamite – which would indicate a level of sophistication on the part of those who fabricated it.

The car’s owner, Keith Galea, a former prison inmate who was released a few days ago, has been questioned by the police but is not being considered a suspect at this stage. However, the police are looking into several possibilities including that the bomb was inside the van.

Mr Galea left the vehicle only a few minutes before the explosion took place shortly after 9.30 a.m. He had parked in front of a disused garage in Canon Bonnici Street, a few doors up from where his parents live.

When questioned he said he did not know that there was anything at the back of the van, sources said. He insisted that his car, including the back door, had been locked.

Explosives experts are searching for any remains of a detonating device which would have had to be used with the explosive. A mechanical or electrical fault in this device could possibly have triggered the bomb at the wrong time. At the same time, the use of a remote trigger is not being excluded.

The process to determine what type of explosive was used could take long because “there are thousands of different explosive materials which could have been used”.

Debris from the wreck went flying in all directions, with pieces of the car ending up as far away as the entrance of a school 70 metres away. Three people passing by were slightly injured. The story would have been very different had the bomb gone off earlier when children would have been making their way to school.

The blast was heard from as far as Birkirkara. Window panes were shattered but a van parked next to the vehicle that exploded only had a shattered windscreen.

Most of the houses had repaired their damaged window panes by yesterday morning and there was little to show that there had been an explosion there the day before.

Forensic expert Anthony Abela Medici, backed by several years of experience in the field, argued that it must have been a bomb with highly explosive material.

Judging by footage and photographs he had seen on the media, since he is not involved in the case, Dr Abela Medici agreed it looked like it was “very unlikely” to have been planted in a few minutes.

This indicates, he said, that it was either being transported or else the person who placed it got the timing wrong.

Such a bomb would have to be manufactured by experienced people, especially because high-explosive material and the detonators to set it off are not so easily available.

Dr Abela Medici said this explosion reminded him of a similar car bomb that killed Emanuel Micallef in December 1969 in Paola. That time, however, the bomb was connected to the engine and went off when the ignition was switched on.