At least 27 people, including 19 police and other government personnel, were injured when a large pile of confiscated fireworks exploded in the southern Philippines, damaging houses, hotels and an international airport.

Two of the victims of Monday afternoon’s explosion were in a serious condition in hospital in the southern port city of Zamboanga, where the mayor ordered an investigation into why the planned controlled destruction of the fireworks by police ordnance experts turned into a massive blast.

Police explosives experts were piling the fireworks in a clearing near a marine firing range for a controlled detonation when the large heap, which had been doused with water, suddenly exploded.

The blast was so powerful that it shattered windows nearly two miles away, according to officials and witnesses.

The passenger terminal at Zamboanga international airport, more than a mile from the blast, sustained minor damage but no injuries or flight delays were reported, the Civil Aviation Authority of the Philippines said.

The illegally manufactured firework had been taken from a warehouse in Zamboanga city where an accidental explosion on June 29 left five people dead and several others injured.

Two controlled destructions of the fireworks prior to Monday were conducted without any incident, Zamboanga officials said.

Many superstitious Filipinos set off powerful firecrackers, especially on New Year’s Eve, believing that noisy celebrations — largely influenced by Chinese tradition — drive away bad luck and evil.

The dangerous tradition has abated due to government restrictions and hard economic times but has persisted in many areas.