Angry villagers stoned a tsunami warning siren in Aceh province after it accidentally went off, triggering panic in the region hardest hit by the 2004 killer waves, an official said Thursday.

Several false alarms in Kaju district early Monday sent thousands of people fleeing to high ground before they were finally urged by police to return home. Roads were clogged with motorbikes and cars for more than an hour.

When another siren sounded in nearby Lhoknga later that afternoon, frustrated residents threw rocks at its electrical panel, said Syahnan Sobri of the local Meteorological and Geophysics Agency.

"It was too high up, so they stoned it," he said, adding that technicians were being sent to the scene to survey the damage.

The 2004 tsunami killed some 230,000 people in 12 nations, almost half of them in Aceh.

The country is establishing a nationwide tsunami warning system with foreign funds, but not all of its coastline is covered.