HONG KONG - Taiwan was shaken Wednesday by its most powerful earthquake in 25 years, a major trembler that killed at least nine people, injured a thousand more, collapsed hundreds of buildings, and triggered tsunami warnings across the region.

Some 143 people, many of them tourists in badly-damaged hotels, were feared trapped in the ruins, the Taiwan National Fire Agency reported.

Rescue efforts were underway to free 71 workers trapped in two rock quarries in the hardest-hit Hualien region, the NFA said. There were also reports that multiple people were trapped in eight collapsed tunnels in and around Hualien City, about 70 miles southeast of the Taiwanese capital Taipei.

The 7.4 magnitude quake happened around 8 a.m. local time (8 p.m. Tuesday ET) at a depth of about 21 miles, according to the U.S. Geological Survey. The epicenter was about 11 miles south-southwest of Hualien City, on the island's Pacific coast.

It was the strongest earthquake to hit Taiwan since 1999, when a 7.6 magnitude tremor killed about 2,400 people, said Wu Chien-fu, director of Taiwan's Seismological Center.