Pakistan's military says a roadside bomb targeting a security vehicle has killed three army officers and an enlisted soldier in a troubled northwestern district bordering Afghanistan.

In a statement, it says four soldiers were also wounded in Friday's attack in North Waziristan.

The military identified the slain officers as Lt. Col. Karim Baig, Maj. Moeez Maqsood and Capt. Arif Ullah, who were traveling in the area of Kharkamar. Kharkamar is where ethnic tensions with minority Pashtuns have flared since last month, when security forces arrested some suspects for their alleged involvement in previous attacks on troops.

Authorities say two lawmakers led a mob attack on a military post at the time to get the suspects released, triggering a shootout that wounded five soldiers and killed several assailants.

The lawmakers face trial for inciting violence.