BANDA ACEH, Indonesia (AFP) — Tearful mourners prayed Thursday as ceremonies began across Asia to remember the 220,000 people who died two decades ago when a tsunami hit coastlines around the Indian Ocean, in one of the world’s worst natural disasters.

On 26 December 2004, a 9.1-magnitude earthquake off Indonesia’s western tip generated a series of massive waves that pummeled the coastline of 14 countries from Indonesia to Somalia.

In Indonesia’s Aceh Province where more than 100,000 people were killed, a siren rang out at the Baiturrahman Grand Mosque to kick off a series of memorials around the region including in Sri Lanka, India and Thailand, which the tsunami hit hours later.

“I thought it was doomsday,” said Hasnawati, a 54-year-old teacher who goes by one name, at the Indonesian mosque which was damaged by the tsunami.

“On a Sunday morning where our family were all laughing together, suddenly a disaster struck and everything’s gone. I can’t describe it with words.”

Some mourners sat and cried at Aceh’s Ulee Lheue mass grave, where around 14,000 are buried, while some villages held their own prayers around the province as they remembered the tragedy that devastated entire communities.

Indonesians will later visit a larger mass grave and hold a communal prayer in provincial capital Banda Aceh, while beachside memorials and religious ceremonies were starting in Sri Lanka, India and Thailand, some of the worst-hit countries.

Victims of waves as high as 30 meters included many foreign tourists celebrating Christmas on the region’s sun-kissed beaches, bringing the tragedy into homes around the globe.

The seabed being ripped open pushed waves at double the speed of a bullet train, crossing the Indian Ocean within hours.