People hug at the Margit bridge on the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
People hug at the Margit bridge on the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
People gather at the Margit bridge on the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
People gather at the Margit bridge on the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
A mother and child watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
A mother and child watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
Members of the rescue crew sit on a floating barge on the Danube after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
Members of the rescue crew sit on a floating barge on the Danube after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
People line the banks of the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
People line the banks of the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP
An ambulance parks at a hotel where the survivors are staying in Budapest, Hungary. Survivors of a South Korean tour boat sinking in Budapest say they were lucky to grab onto a drifting lifeboat while looking in horror as others around them struggled in the dark, rainy waters, shouting for help. Picture: Ha Chae-lim/Yonhap via AP
An ambulance parks at a hotel where the survivors are staying in Budapest, Hungary. Survivors of a South Korean tour boat sinking in Budapest say they were lucky to grab onto a drifting lifeboat while looking in horror as others around them struggled in the dark, rainy waters, shouting for help. Picture: Ha Chae-lim/Yonhap via AP
The redacted list of South Korean tourists is displayed at the Very Good Tour agency headquarters in Seoul, South Korea.  Picture: Ahn Young-joon/AP
The redacted list of South Korean tourists is displayed at the Very Good Tour agency headquarters in Seoul, South Korea. Picture: Ahn Young-joon/AP

Seoul, South Korea — Survivors of a South Korean tour boat sinking in Budapest say they barely managed to grab onto a drifting lifeboat while looking in horror as others around them struggled in the dark, rainy waters, shouting for help.

Only seven among 35 people, 33 of them South Koreans, were rescued. Seven others have been confirmed dead and 21 are missing.

Survivors said their small sightseeing boat almost finished its hourlong night tour of the Hungarian capital on Wednesday and was almost at a stop when a larger cruise ship hit it under a bridge near the riverbank parliament building, a city landmark. They said about 20 people were on the deck taking photographs or preparing to disembark. The others were in the cabin.

"I saw that big cruise ship coming closer to us but I had never imagined it would ram our boat," said a 31-year-old South Korean surnamed Jeong. She was quoted by South Korea's Yonhap news agency.

Jeong said she and others on the deck were thrown into the cold Danube waters by the impact of the collision. Police said it took only seven seconds for the boat to overturn and sink.

She said she saw a lifeboat drifting near her and managed to get hold of it. She threw a rope to another South Korean tourist surnamed Yoon, who was close to her.

Rescuers stand next to oxygen cylinders for divers as they prepare to recover a capsized boat under Margaret Bridge in Budapest. Seven people are confirmed dead, all of them South Koreans. Picture: Zoltan Mathe/MTI via AP

"Our boat was turned over in an instant and began sinking," Yoon, 32, told Yonhap. "All those on the deck fell into water and I think those staying in the cabin on the first floor couldn't probably get out of the ship swiftly."

While holding onto the lifeboat together, Jeong and Yoon said they shed tears when they saw the heads of other people coming up and down in the fast-moving river.

"The people plunged into the river in the darkness and shouted 'Help me!' while floundering in the waters. But I couldn't do anything for them," Jeong said, crying.

A vessel with a crane approaches the site of an accident on the Danube river after a boat capsized in Budapest, Hungary. Picture: Marko Drobnjakovic/AP

Another survivor surnamed Ahn, 60, said a crewmember of another sightseeing boat sailing nearby extended a hand to him after he was tossed into the river. But he lost grip and was carried away by waters before he got hold of a drifting plastic object.

Yoon said rescuers were only able to pick up those who were in the lifeboats or clinging to them, or who held the hands of people extended from other boats nearby. Yoon said she saw the cruise ship that rammed her boat keep sailing without taking any rescue steps after the collision.

Police launched a criminal investigation and late Thursday detained and questioned the Ukrainian captain of the cruise ship. The 64-year-old man is suspected of endangering water transport leading to a deadly mass accident.

People line the banks of the Danube as they watch rescue crews at work after a vessel capsized in Budapest. Picture: Marko Drobnjakovic/AP

Hungary's state TV reported that all the seven rescued have been released from the hospital except one who is being treated for broken ribs.

Thirty South Korean tourists were aboard the sightseeing boat along with two guides and a photographer, all South Korean nationals. Two Hungarian crew on the boat are among the 21 missing.

The South Koreans, mostly family groups, were on a package tour of Europe. Yoon was traveling with her mother, aunt and uncle. After she was rescued, she called her father in Seoul to tell him that she and her mother survived. The fate of her two other relatives is unknown.

Yoon's father, Yoon Seung-yong, told the Seoul-based Hankyoreh newspaper that his daughter felt guilty because she had organized the trip. "She cried and said, 'Dad, what should I do? I think this happened because of me.'"

It was still unclear what exactly caused the collision. A preliminary investigation showed that none of the South Koreans was wearing a life jacket at the time of the incident. Some experts in South Korea also raised questions over why the boat tour was allowed to proceed in the heavy rain with strong currents and compromised visibility.

"There's always a possibility of accidents when you decide to sail in those conditions," said Yun Jong-hwui, a professor at the Korea Maritime and Ocean University.

AP