Crowds gathered on the streets of San Francisco early Tuesday to recall the earthquake and fires that devastated the city 100 years ago. The wreath-laying ceremony honored the victims, and celebrated the spirit of the survivors.

San Francisco Mayor Gavin Newsom, right, listens to earthquake survivor Chrisse Martenstein, 109, talk about her memories on the centennial anniversary

The crowds gathered at Lotta's Fountain, a bronze-colored monument where, 100 year ago, people came for news about their loved ones. At 5:12 in the morning, San Franciscans observed a minute of silence, as a bell tolled.

Then police and fire sirens wailed as three horse-drawn fire-trucks arrived.

The 1906 quake, at magnitude 7.8, destroyed or damaged buildings throughout the city, but most of the devastation was caused by major fires that burned for three days. Broken water lines left firefighters nearly helpless.

Eleven centenarians, who survived the 1906 disaster, took part in the ceremony.

More than 3,000 people died in the quake and fires, and more than half of the city's population of 400,000 was left homeless. But the city quickly recovered, and by 1915, hosted an international exposition to celebrate completion of the Panama Canal a year earlier.

The earthquake was one of the most expensive disasters in U.S. history. Seismologists say the region will always be unstable, and that it is only matter of time before another major earthquake again rocks San Francisco.