ISLAMABAD, Pakistan (CNN) -

Pakistani forces have killed at least 19 militants as part of their offensive in the country's tribal region, the military said in a statement Saturday.

The operation, in North Waziristan, includes airstrikes and artillery shelling.

A Pakistani Taliban leader known as Commander Umer was killed Friday evening on the outskirts of Miranshah, according to the military.

A prominent al-Qaeda commander, who was not named, has been arrested while trying to flee northwestern Pakistan and security forces determined during his interrogation that he is an expert in explosives.

The group, formally known as Tehreek-i-Taliban Pakistan, is a coalition of militant groups. It was founded in 2007, seeking to establish its version of sharia law across Pakistan.