WARSAW, Poland -- A 7-year-old child who fell overboard from a passenger ferry in the Baltic Sea and his mother, who jumped into the water after him, are both dead, police said Friday.

Polish police spokesperson Mariusz Ciarka told the TVN24 broadcaster that it was impossible to save the lives of the two, both of whom were Polish citizens.

The tragedy occurred Thursday when the child fell into the water and the mother decided to jump in after him, Swedish Maritime Administration spokesperson Jonas Franzen told The Associated Press. He said the child fell from a height of about 20 meters (65 feet).

Swedish police confirmed that both were dead.

The mother and child were transported separately by helicopter to a hospital in Karlskrona.

Anders Olsson, who was on the rescue helicopter that pulled the woman from the sea, told Swedish radio on Friday that she was “not responsive” and that first aid was administered to her.

In a brief statement Friday, Sweden’s Prosecution Authority said it has launched ”a preliminary investigation where the crime classification is murder, but there is no suspect in the case.”

“The investigation aims to try to clarify what happened,” Prosecutor Stina Brindmark said. No further details were available.

Ships and helicopters from Sweden and from NATO units that were in the area assisted in the rescue operation.