Two other terrorists were also wounded in the armed clash.
The three terrorists killed in the infighting belonged to banned Lashkar-e-Islam.
The clash between proscribed Lashkar-e-Islam and Tauheed-e-Islamd erupted over some dispute in the tribal area.
The armed clashes between terrorist groups often take place over different issues and both the sides suffer losses.
Pakistan army has also expanded its operation against militants to inside areas of Khyber Agency as part of a grand offensive ‘Zarb-e-Azb’ in North Waziristan.