Cairo,October 6 City- A disgruntled Egyptian bus driver working for a private construction company shot dead six labourers and injured 6 others in a suburb of Cairo, a security official said on Tuesday. "The driver, Mahmoud Taha Ahmed Sweillem, pulled over the bus of his company, the Arab Contractors, near October 6 City, whipped out an assault rifle and showered the 22 passengers with bullets," the official said. He added that six workers died immediately as 6 others were carried to nearby hospitals. "Sweillem opened fire randomly with an automatic rifle. The motives behind the crime are unknown," the official said. However, he added, Sweillem appeared to have suffered severe depression after his company transferred him to a new position. "The security personnel managed to arrest him as investigations are underway over why he committed the crime and how he got the gun," the official said. He added that there were women employees in the bus but none of them were hurt. “Among the victims are a financial manager and a head of a department with the company,” the official said. Arab Contractors is one of the largest construction companies in Egypt.