A bridge collapsed into a harbour in north-eastern Taiwan on Tuesday, crushing several fishing boats and trapping some crew members.
At least nine people fell in the water and seven were rescued, Taiwan's Central News Agency said. Six people were reported to be seriously injured.
Divers were searching for those feared trapped in several fishing boats, government officials from the port township of Suao told Reuters.
"The bridge collapsed at around 9.30am while an oil tanker vehicle was on it, setting the vehicle on fire," said Shih I-chun, a mayoral official. "We feared that some fishermen might be trapped in the boats."
The authorities have set up an emergency centre and the military said marines and the navy were helping with the rescue efforts.
"Saving life is priority," Taiwanese leader Su Tseng-chang said in a Facebook post. "I will ask related authorities to make all effort for the rescue."
The collapse of the Nanfangao Bridge, which carries traffic over the busy fishing port, damaged three fishing boats and two vehicles, including the tanker, the officials said, though the reason for the collapse in clear weather was not immediately clear.
Late on Monday, Typhoon Mitag, with maximum winds of 162kph, swept past north-eastern Taiwan, injuring 12 people and cutting power to more than 66,000 homes. More than 150 flights were cancelled.