An Indian engineer was shot dead and five other people were injured when a "psychologically disturbed" security guard opened fire at an oil field in south-eastern Yemen on Saturday, police said. Police officials told Deutsche Presse-Agentur dpa that the injured men were two Britons, an American, a Tunisian and a Yemeni, dpa reported. The shooting occurred at the Jannah oil field in the oil-rich province of Shabwa, around 470 kilometres south-east or the capital Sana'a. The man, armed with a rifle opened fire randomly at the men as they stepped out of a helicopter owned by the US oil firm, Occidental Petroleum Company, after it landed at a small airport inside the oil field. The attacker was arrested on the premises after other guards shot him in his legs. Police officials said the motives for the crime were believed to be criminal and personal. The interior ministry said primary investigations showed that the assailant, identified as Jameel Mohammad al-Raye, was "psychologically disturbed". The official Saba news agency said the injured men were all in critical condition and that they were airlifted to Sana'a for treatment. Names of the victims were not released, and company officials refused to comment.