A man has died after 35 adults and children were discovered Saturday in a shipping container at the Tilbury Docks in Essex, England, BBC News reported. About 19 people are being treated in hospital for serious health problems. The ship involved was being unloaded by Port of Tilbury authorities following its arrival from Zeebrugge in Belgium.

The Essex Police force has launched an investigation, aided by staff of the Port of Tilbury, U.K. Border Force and East of England Ambulance Service.

“Thirty-one people, including adults and children of both genders, were found inside,” a police representative said. That number has since been updated to 35 people. “One man has sadly died and the others have significant health problems. They are being treated by ambulance crews and are being taken to local hospitals.”

The East of England Ambulance service confirmed that a hazardous area response team has been sent to the Tilbury Docks. The service said in a statement:

“We sent seven ambulances, two rapid response cars, a patient transport services vehicle, two duty operational managers, two basics doctors and our hazardous area response team (Hart), a number of which are still on scene.

“Our initial priority is to assess the level and nature of any injuries and ensure that those people in most need are treated first and taken to hospital. At present, we have taken two patients to Basildon and Thurrock Hospital and are still on scene treating and triaging others.

“We are working closely with other members of the emergency services at the scene, with our priority to ensure patients receive the medical help they need as quickly as possible.”

A representative of Darent Valley Hospital added that it is currently on standby to receive more cases. A casualty bureau has been set up on the docks to treat others with less serious injuries.