Two suicide bombers wearing explosive-laden vests attacked a government building in northwestern Pakistan's volatile Khyber Agency tribal area on Monday, killing at least five people and wounding at least seven more, senior police officials told CNN.

According to a local hospital spokesman, four of the people killed were part of the local tribal police force.

The assailants threw grenades and then entered the Khyber House, home to both local government officials and the tribal court, where prisoners are taken for hearings, the province bomb disposal squad chief, Shafqat Malik, said. Police said after the bombs exploded, militants and Pakistan Security Forces exchanged gunfire.

Iqbal Khan, a local political leader who was in the building the time of the attack, said political parties were meeting there to discuss the "code of conduct" for the upcoming elections. It's unclear whether the militants were targeting the meeting or were trying to help prisoners escape, Peshawar policeman Faisal Murad said.