(CNN) -- Nine people were killed and 20 were wounded in what Iranian authorities call a terrorist attack in the northwestern city of Mahabad, state-run Press TV said Wednesday.
The governor-general of the western Azerbaijan province said the explosion took place at the scene of a military parade and almost all of the victims were women and children, according to the state-run Islamic Republic News Agency.
Iran's Sacred Defense Week ceremonies started Wednesday with the parade of different units of Iran's armed forces in southern Tehran, the IRNA said.
The ceremonies mark the anniversary of the beginning of the country's war with Iraq in 1980.
The conflict lasted eight years and took the lives of an estimated half million people.
No further information was immediately available about Wednesday's attack.