A car bomb exploded Monday at a compound owned by a US-based construction company under contract to the Afghan army, killing at least one person and wounding 15, police said.Five foreigners including Americans and South Africans were among the wounded, a security source at the company told AFP."A small truck packed with explosives detonated between CONTRACK and Najeeb Zarab factories -- one person is dead and 15 others are wounded," Kabul police chief Mohammad Ayoub Salangi told AFP."We don't yet know whether there was someone in the truck or it was detonated remotely. We are investigating this right now. They were very powerful explosives."CONTRACK is a US-owned company which builds Afghan army and police facilities, an employee said."We were sitting in the office. There was a massive explosion. The ceiling collapsed over us and 10 to 12 Afghans in the office were wounded," he said.There was no immediate claim of responsibility but similar attacks are usually blamed on Taliban insurgents fighting the Afghan government and NATO troops.A spokesman for NATO's International Security Assistance Force confirmed the explosion but said it was not at NATO's Camp Phoenix, which is also in the area in the east of the capital near the scene of the bombing.An AFP reporter at the scene said there were signs of a huge explosion beyond an area blocked off by police, and some bystanders outside the compound had also suffered minor injuries.In May Taliban bombers attacked a heavily fortified guesthouse used by Westerners in the same area.Seven people were killed after attackers disguised in burqas detonated a suicide car bomb and clashed with guards at the "Green Village" complex used by the European Union, the United Nations and aid groups.