In Pakistan, four gunmen armed with grenades and automatic rifles attacked the Stock Exchange building in Karachi today.<br />'' <br />'' They killed two guards and a policeman before being killed by the security forces.<br />'' <br />'' A security official said they had come to carry out an attack inside the building and take hostages inside.<br />'' <br />'' Staff inside took refuge in locked rooms and many were evacuated. Security forces are searching the area.<br />''