The AFP news agency reported Aziz-ur-Rehman, a witness, as saying: "After the blast, there was intermittent firing but since it was dark I was unable to know who was firing."
'Wave of terrorism'
The bomber was believed to have targeted members of the Frontier Constabulary, part of Pakistan's paramilitary force, used to protect diplomatic missions and the homes of prominent figures.
Rehman Malik, Pakistan's interior minister, told reporters that Pakistan's security forces were being targeted by a "new wave of terrorism".
Asif Ali Zardari, Pakistan's president, and Yousuf Raza Gilani, the prime minister, condemned the attack.
The second attack occurred in Miranshah, the main town in Pakistan's semi-autonomous North Waziristan tribal area.
"At least seven civilians, including two children, embraced martyrdom in a suicide attack. Thirty-nine others were injured, including six security forces," the AFP news agency quoted an unnamed security official as saying.
Saturday's bombings were the latest in a wave of attacks that have killed more than 1,700 people across the country since government forces battled with fighters holed up in Islamabad's Red mosque in July 2007.