A POWERFUL EXPLOSION ROCKED THE HEADQUARTERS OF A POLICE ANTI-TERROR SQUAD IN INDONESIA'S NORTH SUMATRA CAPITAL OF MEDAN ON WEDNESDAY, KILLING FOUR OFFICERS AND BADLY INJURING SEVERAL OTHERS. NORTH SUMATRA POLICE SPOKESMAN SENIOR COMMISSIONER ASPAN NAINGGOLAN CONFIRMED THE EXPLOSION HAD KILLED FOUR OFFICERS AND INJURE AT LEAST EIGHT OTHERS. NORTH SUMATRA'S POLICE CHIEF TOLD LOCAL RADIO EL-SHINTA THAT THE BLAST WAS AN ACCIDENT THAT OCCURRED WHEN SOME BOMB-SQUAD OFFICERS AT THE POLICE'S ANTI-TERROR UNIT WERE CONDUCTING A TRAINING EXERCISE. 'AN INVESTIGATION IS NOW UNDERWAY. WE DON'T KNOW EXACTLY WHAT HAPPENED AND WE'RE WAITING THE RESULTS OF INVESTIGATION,' SAID NATIONAL POLICE SPOKESMAN BRIGADIER GENERAL ANTON BACHRUL ALAM. AN EYEWITNESS TOLD JAKARTA'S EL-SHINTA PRIVATE RADIO THAT THE HUGE BLAST TOOK PLACE AT THE HEADQUARTERS OF THE PARAMILITARY POLICES BOMB SQUAD IN MEDAN, AT ABOUT 1:45 P.M. (0645 GMT). 'IT WAS A POWERFUL BLAST,' SAID A RESIDENT WHO IDENTIFIED HIMSELF AS HENDRIK. 'THERE ARE A NUMBER OF POLICE OFFICERS BADLY WOUNDED. SOME OF THEM WITH LEGS BLOWN OFF, SOME WITH HANDS BLOWN OFF,' HE SAID. THE VICTIMS WERE TAKEN TO A NEARBY HOSPITAL, THE REPORTS SAID. --SP 23 43 LOCAL TIME 20 43 GMT