TAINAN, Taiwan, Feb. 5 (UPI) -- A powerful earthquake rattled southern Taiwan early Saturday and caused the collapses of two buildings, witnesses and news media reported.
The first quake, which recorded a magnitude of 6.4, struck about 20 miles away from the coastal city of Tainan at about 3 p.m. EST Friday, the U.S. Geological Survey reported. The quake occurred at about 4 a.m. local time Saturday.
Taiwan's Central Weather Bureau said a second earthquake, measuring 4.3, followed.
No casualties were initially reported but the first quake is said to have caused major damage to infrastructure -- some of which was posted on social media.
Witnesses said one of the collapsed buildings, which stood 17 stories tall, appeared to be a residential tower where emergency crews were pulling out survivors.
Broadcaster ITV reported that hundreds of people could be trapped inside the collapsed buildings.
The earthquake was felt as far away as mainland China, the Los Angeles Times reported. Officials initially reported the earthquake had a magnitude of 6.7.
"It was not a rolling gentle earthquake, but a violent jerking motion," school teacher and former California resident Derek Hoerler said. "The walls were shaking and you could hear the building and windows moving.
"It lasted at least a minute with swaying afterwards. I felt complete terror. ... Biggest earthquake I've felt, and I'm from California."
Taiwanese officials didn't indicate a danger of tsunamis, which often occur following strong earthquakes in coastal areas. No tsunami warning was issued in Taiwan following the quake, BNO News reported.
The earthquake was the second powerful quake to hit Taiwan this week. On Tuesday, a 6.2 magnitude earthquake struck northeast Taiwan.
The Pacific Rim is a hotbed for seismic activity, geologists say. A 7.6 magnitude earthquake rocked Taiwan in 1999, killing more than 2,500 people.