Salim Riaz Khan, a senior police officer in Dera Ismail Khan, said gunmen on motorcycles opened fire on police in a residential area, killing two, AP reported.
He said the bomber then struck at the entrance to the hospital, killing another four police and three civilians who were visiting their relatives.
According to him, eight police were among the wounded, and that many of the wounded were in critical condition.
Inayat Ullah, a local forensics expert, said the female attacker set off seven kilograms (15 pounds) of explosives packed with nails and ball-bearings.
The blast damaged the emergency room and forced it to shut down, according to a hospital official, who said the wounded were taken to a military hospital. The official spoke on condition of anonymity for fear of reprisal.
The Taliban claimed the attack but did not acknowledge that the bomber was a woman. The group has launched scores of attacks going back nearly two decades, but almost all of them were carried out by men.
Pakistan's military has carried out several major operations in recent years against the Taliban and other terrorists in areas along the porous border with Afghanistan. The violence has declined, but the terrorists still make their presence known through occasional attacks.
Later on Sunday, police said they had arrested 16 suspects in the attack, all of whom belong to banned organizations. Police officer Habib Ahmed said authorities also seized weapons during the manhunt.