ISTANBUL, May 20 (Reuters) - A mayor belonging to Turkey's ruling AK Party was seriously wounded in a gun attack in northwest Turkey on Wednesday, a hospital official and local media said, less than three weeks ahead of a parliamentary election.

The private Dogan news agency said Cuneyt Yildiz, mayor of the Gursu district of Bursa province, was shot in his office and that a member of the municipality staff suspected in the shooting had fled the scene.

Yildiz's bodyguard was also wounded in the attack and the two were being treated in a nearby hospital, according to broadcaster CNN Turk.

The motive for the attack was not immediately clear.

Tensions have risen in Turkey ahead of the June 7 election,

which the AK Party founded by President Tayyip Erdogan is on course to win comfortably.

On Monday, simultaneous bomb blasts hit the offices of a pro-Kurdish party in two cities in southern Turkey, wounding six people. (Reporting by Humeyra Pamuk; editing by Ralph Boulton; Writing by Daren Butler; editing by David Dolan)