Chinese President Xi Jinping has ordered that no efforts be spared in rescue work, although the official Xinhua news agency said bad weather was making rescue efforts more difficult.

Some passengers are still alive inside the hull of a passenger ship carrying 458 people, many of them elderly Chinese tourists, that capsized on the Yangtze River, state media said on Tuesday, June 2.

The microblog of the official People’s Daily newspaper said some passengers were still inside the Eastern Star, while the official Xinhua news agency said rescuers could hear people calling for help from inside the four-deck ship.

The captain and chief engineer of a vessel carrying 458 people have been detained by police for questioning, the state-run Xinhua news agency said on its official microblog on Tuesday.

Premier Li Keqiang was heading to the scene of the accident in central Hubei province, Xinhua said.

Xinhua, citing the Yangtze River navigation administration, said those rescued from the Eastern Star included the ship’s captain and engineer, who said the vessel sank quickly after being caught in what it said was a cyclone.

State radio reported that the ship sank within about two minutes and that no distress call had been issued. About 20 people had been rescued, Xinhua said later on Tuesday.

The official People’s Daily said seven people had swum to shore to raise the alarm.

The Hubei Daily, another official publication, said the ship had capsized and that the hull of the stricken vessel was still visible in the river, where the water was about 15 metres (50 feet) deep.

Weather forecasts said heavy rain was expected on Tuesday.

Among those on board the ship were 406 tourists, aged from around 50 to 80, on a tour organised by a Shanghai tour group, and 47 crew members, the People’s Daily said.

Dozens of vessels are helping in the search and rescue, including fishing boats, Xinhua said. At least 20 divers were also on their way to the scene and about 100 fishing boats were helping in rescue efforts, according to the Hubei Daily.

The vessel was heading to southwest China’s Chongqing city from Nanjing, capital of east China’s Jiangsu Province. It sank at around 9:28 p.m. local time in the Jianli section of the river. It had the capacity to carry more than 500 people, the People’s Daily said.

The Eastern Star was owned by the Chongqing Eastern Shipping Corporation, which runs tours along the Three Gorges area along the Yangtze river. The company has been operating since 1967, the Hubei Daily said.