KARACHI- At least four seminary students were killed and 16 others injured in grenades attack on a madrasah today.According to reports, unknown miscreants on motorbike hurled multiple hand grenades on Jamia Masjid Islamiya Tahiria and adjacent madrasah at Frontier Morr in Orangi Town area. Police and rescue officials said the students killed and injured are aged between 8 and 12 years. Two of the deceased were identified as Umer Khan and Suleman. Rescue teams shifted the injured to Abbasi Shaheed Hospital and Civil Hospital where four of the injured were said to be in critical condition. Police and Rangers personnel have cordoned off the blast site. Meanwhile, Sindh Governor Ishratul Ibad took notice of the incident and sought report from Inspector General of Police. The seminary is headed by famous Islamic scholar Maulana Ubaidullah but motive behind the attack could not be ascertained as yet.