More than 430 people are feared dead in China's worst shipping disaster in decades.
The Eastern Star capsized on the Yangtze River yesterday. Rescue teams have saved around a dozen people and recovered five bodies so far.
State media reported that 458 people had been on board the ship, many of them elderly Chinese tourists.
Distraught relatives of some of the passengers scuffled with officials in the city of Shanghai, where many of those on board booked their trips, angry about what they said was a lack of information about their loved ones.
The Xinhua news agency said rescuers could hear people calling for help from inside the ship's hull and television showed rescuers trying to cut through it with an angle grinder.
Divers pulled a man and a 65-year-old woman alive from the capsized four-decked tourist ship, Xinhua said.
Dozens of rescue boats battled wind and rain to reach the ship, which lay upturned in water about 15m deep.
The disaster could bring a bigger toll than the sinking of a ferry in South Korea in April 2014 that killed 304 people, most of them children on a school trip.
A tour guide told Xinhua the capsize happened very fast and he scrambled out a window in torrential rain clutching a life vest as he could not swim.
President Xi Jinping had ordered that no efforts be spared in the rescue and Premier Li Keqiang went to the scene of the accident in central Hubei province, Xinhua said.
About 60 family members gathered outside a travel agency in Shanghai and demanded information.
The ship's captain and the chief engineer, who were among the few to be rescued, had been detained by police for questioning, Xinhua said.
According to the Yangtze River navigation administration, the pair said the ship sank quickly after it was caught in what was described as a tornado.
Xinhua reported that initial investigations had found the ship was not overloaded and it had enough life vests on board for its passengers. Those rescued were wearing life vests, Xinhua said.
Among those on board were 406 tourists, aged from about 50 to 80, on a tour organised by a Shanghai tour group, along with 47 crew members and five tour guides, the People's Daily said.
State radio said the ship went over in about two minutes and no distress call had been issued. Seven people swam to shore to raise the alarm, media said.
The Eastern Star, which has the capacity to carry more than 500 people, was heading to southwest China's Chongqing city from Nanjing, capital of east China's Jiangsu Province.
It sank at around 9.28pm local time in the Jianli section of the river.
Accidents of this magnitude are uncommon in China, where major rivers are used for tours and cruises.
The incident is the worst on the Yangtze since a tug undergoing sea trials sank in January, killing 22 of the 25 people on board.
The Eastern Star is owned by the Chongqing Eastern Shipping Corporation, which runs tours along the Three Gorges area along the Yangtze river.
Major boat disasters in Asia pic.twitter.com/yhmIMFgx0f
— Agence France-Presse (@AFP) June 2, 2015