A powerful blast rocked the border town of Islam Qala in the western Herat province 640 km west of Kabul on Monday, injuring three people, a local official said. \"The blast happened at around 09:50 a.m. local time near a border police checkpoint in the border town of Islam Qala, leaving three people injured,\" the official told Xinhua but declined to be identified. He also noted that authorized officials would release the details after completion of investigation.