Twelve people remained unaccounted for as of Saturday morning, more than 72 hours after Wednesday's powerful Taiwan earthquake. The chances for survival drop sharply after that time.

Authorities say that as of 9 a.m. local time, 12 people were unaccounted for, up two from Friday. They included foreigners.

Many of them are believed to have been around Taroko Gorge, a popular tourist destination, in the eastern county of Hualien near the epicenter.

Before rescuers set out amid falling rain to search for six individuals unaccounted for near the gorge, the top county official spoke at a meeting and noted that 72 hours and 50 minutes had passed since the quake. The official underscored the need to bring the missing to safety as quickly as possible.

The rescue team is planning to use heavy machinery to accelerate the search. It says the operation must proceed carefully in consideration of the overall situation, including rain.

The leader of the rescue unit said the biggest obstacle is the weather and continuing tremors. But he vowed to do all they can to overcome difficulties and find those who need rescue.