Four suspected terrorists, including the alleged mastermind of a deadly suicide attack last year in Orakzai, were killed in an 'encounter' with security forces in Hangu on Wednesday.

A local police official, Muhammad Khalid, confirmed to the Associated Press that security forces had conducted a raid in Hangu. A security source told DawnNewsTV that the raid was carried out after a tip-off was received that the house was serving as a militant hideout.

The suspected terrorists opened fire on security forces during the raid, the source said, adding that four 'terrorists' were killed in the ensuing encounter.

A civilian was also accidentally killed in the shootout, AP reported.

Khalid identified one of the militants killed as Muhammad Islam and said that he was responsible for orchestrating the Nov 23 suicide attack near an imambargah in lower Orakzai's Kalaya Bazaar that left at least 32 people dead and 31 injured.

The security source told DawnNewsTV that Islam had ties to the banned Tehreek-i-Taliban Pakistan.