Aftab Ahmed Khan Sherpao, Pakistan's interior minister, said one policeman and one civilian were killed.
"Unrest and chaos"
Farid Mahsud, a doctor at the city's main hospital, identified the civilian as a worker at a nearby petrol station.
Sherpao blamed the attack on, "anti-state elements trying to create unrest and chaos".
He said the Pakistani government was "firm in its resolve to uproot terrorism and extremism".
Some analysts have said suicide attacks last year in the northwest of Pakistan were a result of conflict in the tribal lands along the border with Afghan border where the Pakistani army is fighting pro-Taliban forces and suspected members of al-Qaeda.
Security officials in Dera Ismail Khan said that six people had been arrested on Sunday on suspicion of planning suicide attacks and explosives had been seized from the suspects.
On Friday, a suicide bomber killed himself and a guard outside the Marriott Hotel in Islamabad, while on Saturday a suicide bomber killed 15 people, including a city police chief, in the northwestern city of Peshawar.
Sherpao said investigators were still trying to determine who was behind the two attacks.
In a separate incident on Monday, 13 people were hurt when two rockets were fired outside a Shia religious centre in the northwestern town of Bannu, said Asif Gohar, a police official in the town.