Croatian police have arrested a first officer of a catamaran following a collision near Split on Sunday that resulted in the sinking of a sailboat carrying Czech nationals. The incident led to the deaths of four Czech citizens. Four other individuals were rescued and transported to a hospital for medical treatment. Croatian public broadcaster HRT reported the arrest on Wednesday. Authorities are investigating the circumstances surrounding the collision to determine the cause and any potential negligence. The incident has prompted an investigation into maritime safety regulations in the area. Further details regarding the charges against the officer have not yet been released.