Rescuers in boats work to prepare to recover a capsized boat under Margaret Bridge in Budapest, Hungary, May 30, 2019.
Rescuers in boats work to prepare to recover a capsized boat under Margaret Bridge in Budapest, Hungary, May 30, 2019.

Hungarian police have arrested the captain of the cruise ship that collided with a smaller tour boat on the Danube River late Wednesday, causing the boat to sink in just seconds.

Seven people are confirmed dead and 21 others missing. All but two people on the boat were South Korean tourists.

Police arrested the Ukrainian captain of the Viking cruise ship, identifying him as Yuriy C.

Police say he is suspected of "endangering waterborne traffic resulting in multiple deaths."

People stand on the Margaret Bridge to watch the r
People stand on the Margaret Bridge to watch the recovery operations for a capsized boat in Budapest, Hungary, May 30, 2019.

Investigators say the Viking ship and the tour boat, Mermaid, were sailing side-by-side on the Danube in central Budapest when both vessels arrived at pillars under the Margit Bridge.

The Mermaid turned in front of the Viking ship which struck the boat and capsizing it. Police say the Mermaid sank in just seven seconds, giving passengers and two Hungarian crewmembers almost no time to get to safety.

Hungarian rescuers say heavy rain and the Danube's strong currents are hampering their efforts. They have extended their search downriver into Serbia. 

South Korean President Moon Jae-in has sent a delegation of Korean officials and experts to Budapest to help.