Hope began to fade Friday morning in the search for 21 people feared lost after a boating accident in Budapest's Danube River.
There were 33 South Korean tourists and two Hungarian crew members aboard the Hableany, which translates to "Mermaid," when it collided with Viking Sigyn, a luxury cruise liner, Wednesday evening. Seven people have been confirmed dead.
The 86-foot-long tourist vessel sunk in about seven seconds after colliding with the 443-foot-long cruise liner.
A survivor from the Hableany told Seoul-based Yonhap News Agency that the other ship just continued on its way and didn't stop to attempt a rescue.
Police on Friday arrested the 64-year-old Ukrainian captain of the Viking Sigyn, identified only as Yuriy C. Both captains, police said, were experienced sailors.
Authorities located the wreckage of the Hableany on the riverbed near the Margaret Bridge in central Budapest after several hours, but it may take a week to dredge up the 70-year-old boat, Yonhap reported.
Rescue operations have expanded nearly 20 miles downsteam, as South Korea has requested neighboring countries -- Serbia, Croatia, Romania, Ukraine -- assist in finding those still missing.
Of the seven recovered bodies, one was found more than 7 miles downstream about 2 1/2 hours after the collision, Hungarian police reported. Recent river flows have reached almost 7 mph.
"Those contributing to the search will continue to do everything possible," police said in a statement.
A South Korean task force and emergency rescue team headed by Foreign Minister Kang Kyung-wha arrived in Budapest around 8:40 a.m. local time on Friday. Representatives and employees of the company, Very Good Tour Agency, that arranged the trip also arrived in Hungary to assist survivors.
"I'd like to express my sincerest condolences to the victims and their families," Lee Sang Moo, executive director of Very Good Tour Agency, said at a press conference at company headquarters on Thursday. "Our representatives and employees will do everything they can to minimize the damage caused by the accident using every means and resources possible, regardless of the cost."
More than 40 family members of passengers on the Hableany departed South Korea on Thursday, with some arriving in Budapest on Friday morning.
South Korea's Foreign Ministry said none of the passengers on the sunken boat were wearing life jackets.
ABC News' Hakyung Kate Lee and The Associated Press contributed to this report.