It was the second serious incident involving a TransAsia Airways plane in a few months after another flight operated by the domestic airline crashed in July during a storm, killing 48 people.
Dramatic amateur video footage from Wednesday's accident showed the TransAsia ATR 72-600 turboprop plane hit the road bridge as it banked side-long towards the water, leaving a trail of debris including a smashed taxi.
The accident happened just before 11:00 am (0300 GMT), shortly after Flight GE235 left Songshan airport in northern Taipei en route to the island of Kinmen, with 58 people on board including five crew members.
Lin Kuan-cheng, an official at the national fire agency, told AFP that one person was confirmed dead and another 10 were showing "no signs of life". Unconfirmed TV reports said 12 people had been killed.
A senior rescuer at the site said that 27 of the 58 people aboard -- many of them Chinese tourists -- had been retrieved from the wreckage.
The remaining 31 people are thought to be trapped inside the submerged front section of the plane.
![Taiwan plane crash](http://img.astroawani.com/2015-02/41423040047_freesize.jpg)
An image showing how the aircraft clipped the road bridge. - Taiwan CTITV
"The focus of our work is to try to use cranes to lift the front part of the wreckage, which is submerged under the water and is where most of the other passengers are feared trapped," the rescue official told reporters at the scene.
China's Xiamen Daily said on a verified social media account that there were 31 mainlanders on board, part of two tour groups from the eastern Chinese city.
"All their phones were powered off because they were on board a plane, so we haven't been able to contact them," the daily quoted an unnamed representative of one of the tour agencies as saying.
Xiamen is in Fujian province, which lies across the Taiwan Strait from the island.
An employee of one of the tour agencies, surnamed Wen, told AFP that it had 15 clients, including three children under 10, and a tour leader on board.
"It's an emergency," she said. "We're working with different work teams. We’re trying to arrange for the relatives to go to Taiwan."
Race against time
Rescuers standing on large sections of broken wreckage tried to pull passengers out of the plane with ropes. Those who were rescued -- including two children -- were put in dinghies and taken to the shore.
Some were then loaded on stretchers.
Aviation officials said the plane crashed minutes after taking off Songshan airport, after losing contact with the control tower.
Eight rescue boats and more than 15 ambulances as well as around 100 soldiers were working on the rescue operation, an AFP reporter at the scene said.
The plane wreckage remained in the middle of the river, surrounded by dinghies.
Lin Chih-ming, head of Taiwan's Civil Aeronautics Administration, said the ATR 72-600 was less than a year old and was last serviced just over a week ago.
The pilot had 14,000 flying hours and the co-pilot 4,000 hours, Lin said.
In last July's crash, the 48 people were killed when another domestic TransAsia flight crashed onto houses during a storm on the Taiwanese island of Penghu.
The ATR 72-500 turboprop plane deviated off course before plunging into the houses after an aborted landing during thunder and heavy rain as Typhoon Matmo pounded Taiwan at the time.
The flight's pilots could not see the runway but had continued to descend anyway, Taiwanese authorities said in December. Two French nationals were among the dead.