Witnesses said a huge explosion damaged an administration office, shops, a local jail and other buildings in the small town not far from the border with Afghanistan.
There was no immediate claim of responsibility. Mohmand is a Taliban stronghold.
Pakistani leaders this week called for a national conference to develop a strategy to counter the Islamist threat after a twin suicide attack killed 43 people at a shrine in Lahore on 2 July.
The government said all major parties would be invited to the conference. The details and date of the possible conference have not been made clear.