KARACHI - A low-intensity blast occurred outside the countrys largest video CDs market, Rainbow Centre, killing one person and injuring 19 others, here on Thursday evening. The blast hit the pushcarts in front of the Rainbow Centre. Following the blast law-enforcement agencies, bomb disposal squad and rescuers of various welfare organisations reached the spot and shifted the wounded to different hospitals of the city. Hospital sources said as many as nine injured persons were brought to the hospital while five of them were discharged after first aid. Police said that investigation is underway and experts of BDS examined the nature of the blast. Eyewitnesses, when asked, said that there were some five to six men sitting where unknown culprits had thrown the hand-grenade and managed to flee. Crime scene revealed that pellets were used in the cracker which caused the little damage to the shops of centre. In the aftermath of the blast, commercial and non-commercial activities were completely suspended in the area. Heavy contingents of police and Rangers reached the spot and cordoned off the area while BDS experts and teams of other agencies colleted the explosive samples from the crime scene. It is pertinent to mention here that Rainbow Centre administration had received several threatening calls and letters earlier and a number of shopkeepers have put off their businesses because of the frequent threats.