At least two persons were killed and 21 others injured when a suicide car bombing hit a paramilitary force's headquarters in Pakistan's southern port city of Karachi on Thursday morning, said a spokesman of Rangers, a paramilitary force in the country. According to the spokesman, two people including the suicide bomber himself were killed and 21 others injured in the blast and three to four people among the injured were critically wounded. He said no rangers got killed in the blast, but local police insisted that one ranger died in the blast. The spokesman did not give the details about the wounded people. Local police said the injured include at least eight rangers and three policemen and some other civilians. Two suspects were arrested, said the Rangers spokesman. They were arrested while making videos of the blast victims at Abbasi Shaheed Hospital, he said. The two suspects claimed they were policemen, but actually they were not, he added. According to police and local media reports, the blast took place at about 6:55 a.m. local time when a suicide bomber rammed his explosive-laden white colored mini truck through the main gate of the Rangers headquarters in North Nazimabad of Karachi and exploded right in front of a four-storeyed building in the headquarters. The Rangers spokesman said that the building targeted was a residential building inside the headquarters. Police said that there were an estimated 150 people inside the building when the blast took place. The suicide bomber failed to reach the building before the explosion, said Inspector General Sindh Fayyaz Laghari. Otherwise the casualties could be much higher, he said. Bomb disposal squad officers said that the bomber hid the explosives under the vegetables on the mini truck and an estimated 100 kg explosives were used. Parts of the body of the suicide bomber have been collected to determine his age, they said. Both Pakistani President Asif Ali Zardari and Prime Minister Ashraf condemned the attack shortly after the blast was reported. Pakistan Taliban has reportedly claimed the responsibility for the attack. This is the second attack launched by Pakistan Taliban over the last two days. Earlier on Wednesday morning, a suicide car bombing hit a police vehicle in Pakistan's northwest city of Peshawar, leaving six people including three cops killed and over 30 others injured.