Explosives planted in a car went off in a busy area of Karachi . All four people killed are civilians , police say . Balochistan has experienced deadly sectarian violence against its Shiite Muslim minority and is also home to separatists who carry out attacks . No group has claimed responsibility for the attack .
Explosives planted in a car went off in a busy area of Karachi . All four people killed are civilians , police say . No group has claimed responsibility for the attack .