A bomb killed seven people near a Shiite Muslim procession in Dera Ismail Khan Saturday despite a security crackdown, the latest attack on the minority during their holy month of Muharram.Four boys were among the dead and 30 other people were injured when the remote-controlled bomb packed with ball bearings exploded on the outskirts of Dera Ismail Khan in Khyber Pakhtunkhwa province, police said.Authorities subsequently ordered heightened security, with services for mobile phones -- which are often used to trigger bombs -- suspended in major cities.But that did not prevent Saturday's attack. Police said a 10-kilogramme (22-pound) bomb was hidden in a dustbin on the procession route and its powerful blast could be heard several kilometres away."The death toll is now seven, four of them are children," local hospital chief Aziz Baluch told AFP. "Four of the wounded were in critical condition, they have been shifted to the central city of Multan."Akhtar Nawaz, another official at the state-run district headquarters hospital said three children were dead on arrival and the four other people died after being admitted.City police chief Khalid Suhail said the dead children were aged between six and 11 years. "They were young boys," he said.Mobile and wireless phone services were temporarily blocked in the commercial capital Karachi, the southwestern city of Quetta and several cities and towns in Khyber Pakhtunkhwa and Punjab provinces as well as in parts of the capital Islamabad.It is the second time Pakistan has shut down mobile networks during Muharram.Interior Minister Rehman Malik has strongly condemned the D.I. Khan blast near mourning procession and sought detailed inquiry report of the incident from the I.G. Police Khyber Pakhtunkhwa.President Asif Ali Zardari and Prime Minister Raja Pervez Ashraf has strongly condemned bomb blast in D.I.Khan.Expressing grief and sorrow over the loss of innocent lives, the President and PM expressed sympathies with bereaved families and directed the concerned to provide best medical treatment to the injured.They reiterated resolve of the Government to continue its struggle against the militants till its logical conclusion.They said that such nefarious acts can not deter the people and the Government in their fight against the scourge of militancy.