The remote-controlled bomb targeted a vehicle of the security forces in the Datta Khel area near the Afghan border, Xinhua news agency reported.
The injured were taken to a military hospital in Bannu, a city near North Waziristan.
No group has claimed responsibility. The authorities blamed the Taliban for such attacks.
Officials said the security forces were on routine patrolling when their vehicle came under attack.
It is the second attack on security forces in the area in two days. A security personnel was killed and another injured in an attack on Friday.
The security forces, backed by fighter jets, are battling the Taliban and other militant groups in North Waziristan. The operation was launched in June last year after the rare peace talks with the Taliban collapsed.
The army has cleared over 90 percent of the area and a military spokesman said over 2,000 militants have also been killed during the offensive. Some militants have fled to other areas and crossed into the Afghan side of the border, according to security officials.