Security forces Thursday arrested four local suspects following attack on a checkpost early morning that killed three soldiers in Bajaur tribal agency, bordering Afghanistan, said security sources. Four suspects were arrested in a raid in the agency, sources told KUNA, adding that one of the suspects was wounded.On Thursday morning, unknown miscreants attacked a Levies Force checkpost in Charmung area of the agency. There was an exchange of fire between the forces and miscreants that killed three soldiers.