KARACHI/HYDERABAD - A series of blasts occurred on main Railway tracks in Hyderabad and other parts of interior Sindh as well as Karachi early Friday morning which paralysed the Railway traffic with halting of trains of both up and down tracks at different Railway stations causing great hardships to hundreds of commuters for several hours. Besides Karachi, the miscreants planted explosive devices on Railway tracks near Hussainabad in Hyderabad, Nawabshah, Mehrabpur in Naushero Feroze and Ghotki which blew up in a series within half an hour time at about 6 am. In Karachi, at least three persons were injured in twin blasts which exploded at Railway tracks at Omar Colony in the limits of Ferozeabad police station. According to details, two low intensity explosions, which occurred at around 5:55 am, exploded in up and down Railway tracks at Omar Colony. In Hyderabad, the device was planted near the Railway bridge at Hussainabad, which exploded with big bang, causing panic among the residents of Wahdat Colony, Hussainabad, Latifabad and Qasimabad upon which they came out of their residences to inquire about the situation. Heavy contingents of police and Rangers immediately rushed to spot and cordoned off the area. The Bomb Disposal Squad found uprooting of around two feet each up and down tracks and confirmed that blast occurred due to timer device with at least four to five kilograms explosive powder. As a result of damages, caused at the up and down tracks, the Railway traffic was halted at nearby stations. The Railway authorities halted Shah Abdul Latif Express at Kotri Railway Station while Khyber Mail was stopped at Hyderabad Railway Station which later received green signals after repair of the track from Railway engineers for about five to six hours. Similar blasts also occurred at the main Railway tracks near Nawabshah, Mehrabpur and Ghotki Railway Stations within time period of half an hour. After blast in Hyderabad Railway track, many of the passengers of halted trains at Hyderabad and Kotri Railway Stations and returned the tickets while preferring to travel by road.