Kabul, Dec 22 : At least five people were killed and two others injured in a blast in Kabul on Tuesday, police said. According to police spokesman Ferdaus Faramarz, the blast, that targeted a car carrying doctors, took place at Doghabad area in Police District 7, Xinhua news agency. Faramarz confirmed that the doctors had worked in the Pul-e-Charkhi prison, Afghanistan's main jail where thousands, including militants, are held. An investigation was underway, the spokesman added. No group has claimed responsibility so far. Tuesday's development comes after the Interior Ministry on Sunday claimed that 28 civilians were killed and 47 others injured in blasts across the country from December 17-20. According to the Ministry, a total of 37 suicide attacks and 510 blasts have killed nearly 500 civilians and injured more than 1,050 others over the past three months in Afghanistan. A total of 2,117 civilians had been killed and 3,822 injured from January 1 to September 30 this year, according to a report of the UN Assistance Mission in Afghanistan (UNAMA) released in October. /IANS