Two Italian children, who were poisoned by carbon monoxide on a chartered yacht off the Adriatic island of Hvar on August 13, were helicoptered from the city of Split's hospital where they were treated for seven days to Rome after their condition had improved, sources in Split Hospital told state news agency Hina on Wednesday.

The children were admitted to the Split hospital in a critical condition and needed mechanical ventilation due to multiple organ failure. Over the past few days, their condition has improved, and on Wednesday morning they were transported from Split to Bambino Gesu Children’s Hospital in the Italian capital city. They were accompanied by their mother who had suffered from poisoning on the yacht and who was also treated in the Split hospital.

Their father died in the incident.

The owner and the captain of the boat on which that 57-year-old Italian tourist died of carbon monoxide poisoning and six more passengers incurred serious health problems, are under investigation for installing a power unit in the boat’s engine-room, which caused a leakage of poisonous gases.

The 23-year-old owner of the yacht and its 27-year-old captain, both Croatian nationals, were taken in for questioning by police on the island of Hvar and were later released pending further investigation.