The death toll is rising after a 7.2 magnitude earthquake rocked Taiwan, sparking a tsunami warning for the islands of southern Japan and the Philippines.

Taiwan’s fire department reported the casualties as television stations showed footage of buildings at precarious angles in the sparsely populated eastern county of Hualien, near the quake’s epicentre.

Taiwan’s government said four people had died in mountainous Hualien, while more than 50 were injured. At least 26 buildings had collapsed, more than half in Hualien, with about 20 people trapped and rescue work ongoing, it said.

Wednesday’s quake, which knocked out power in several parts of the capital Taipei, hit at a depth of 15.5 kilometres just off the eastern coast of Taiwan shortly before 8am (local time), according to Taiwan’s Central Weather Administration.

“Some people are believed to be trapped. We don’t have more information at the moment,” a local fire department official told AFP in the hours after the tremor.

Other footage showed objects flying from shelves and furniture falling over as buildings shook wildly. Vehicles were smashed and products inside shops sent flying, according to clips aired by local broadcaster TVBS.

“It was very strong,” 60-year-old Taipei hospital worker Chang Yu-Lin said.

“It felt as if the house was going to topple.”

Japan’s weather agency said several small tsunami waves reached parts of the southern prefecture of Okinawa. It later downgraded the earlier tsunami warning to an advisory, and revised the quake’s magnitude to 7.7.

The Philippines Seismology Agency also issued a warning for residents in coastal areas of several provinces, urging them to evacuate to higher ground.

The quake was felt in Shanghai, a Reuters witness said. Chinese state media said it was also felt in Fuzhou, Xiamen, Quanzhou and Ningde in China’s Fujian province.

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Aftershocks could still be felt in Taipei, according to a Reuters witness. At least 25 had been registered by Wednesday afternoon, according to Taiwan’s central weather administration.

China Earthquake Networks Centre recorded five aftershocks of around five magnitude in Taiwan within an hour after the initial quake.

The Taipei city government had not received any reports of damage and the city’s MRT was up and running soon after, while electricity operator Taipower said more than 87,000 households in Taiwan were still without power.

Southern Taiwan Science Park, where semiconductor giant Taiwan Semiconductor Manufacturing Co has a plant, said companies were operating without impact.

TSMC said its safety systems are operating normally.

“To ensure the safety of personnel, some fabs were evacuated according to company procedure. We are currently confirming the details of the impact,” according to the company.

Taiwan’s official central news agency said the quake was the biggest to hit the island since 1999 when a 7.6 magnitude tremor killed about 2400 people and destroyed or damaged 50,000 buildings in one of Taiwan’s worst-recorded quakes.

The CWA said the earthquake registered the second-highest intensity of an “Upper 6” in Hualien county, on the 1-7 intensity scale.

In an Upper 6 earthquake, most unreinforced concrete-block walls collapse and people find it impossible to remain standing or move without crawling, the Japan Meteorological Agency says.

-with AAP