ANKARA, Feb. 2 (Xinhua) -- The Turkish authorities said on Friday that the explosion in a tax office in Ankara was caused by a bomb, not a gas leak as initially reported.

The suspected bomber was gunned down by the police, and eight other suspects were detained, the government of Ankara said in a statement.

The killed suspect, 26, received training in the areas held by Kurdish People's Protection Unit in Syria, and entered Turkey illegally, the statement said.

Security footage showed a man with a bag placing and preparing the bomb at the entrance of the building, it added.

The explosion on Thursday occurred in a boiler room of a tax office in Ankara's Cukurambar district, causing damage to the building and slightly injuring three security personnel.

A loud blast was heard in many parts of the capital city, triggering panic among residents.