One of the bombed houses belonged to Aslam Farooqi, a local Taliban commander, the officials said, but it was not clear if he was among those killed.
Orakzai had been the base of Hakimullah Mehsud, the Pakistani Taliban chief who officials believe was killed in a US missile strike early this year.
The group insists he is alive, but has not provided any evidence to back up its claims.
Elsewhere in Pakistan on Sunday, fighters tried to blow up a Nato oil tanker on Sunday in the southwestern province of Baluchistan.
A police official said a bomb, planted in a lorry's undercarriage, misfired, causing a hole in the tanker and an oil spill.
Violence has surged in Pakistan in recent days as fighters have launched a wave of suicide bombings, killing at least 81 people in one week.
Over the past year, Pakistan has significantly increased operations against fighters in its northwest and tribal belt which Washington has branded an al-Qaeda "headquarters".
The area became a stronghold for hundreds of fighters who fled neighbouring Afghanistan after the US-led invasion in late 2001.
Washington says the fighters use Pakistan's tribal belt to plot and stage attacks in Afghanistan, where more than 120,000 Nato and US troops are helping Afghan forces battle the Taliban.