Two adults and two children have reportedly died on Tuesday while attempting to cross the English Channel, according to French officials.

On Tuesday morning, a boat carrying Iranian migrants capsized in rough weather about one nautical mile off Dunkirk, and a passing sailboat spotted it at about 0930 hours. The regional maritime authority called on good samaritans for assistance, and a nearby fishing vessel and the Dunkirk pilot boat responded, along with the lifeboat Notre Dame des Flandres.

One Belgian Air Force helicopter and several vessels from the French Navy and the Customs Service responded to the scene, and they rescued the survivors.

One woman and two young children died from hypothermia or cardiac arrest after they were pulled from the water, and one additional victim drowned before rescuers arrived. 14 individuals survived and were delivered to emergency medical services personnel on shore.

According to official Herve Tourmente of France’s Nord province, one individual, potentially an infant, is still missing. The search was called off at 1800 hours due to poor conditions and darkness.

In a statement, the Maritime Prefecture of the Channel and the North Sea (Premar Manche) warned other migrants who might plan to cross the Channel that it is one of the world’s busiest sea routes and is known for its challenging, and potentially dangerous, rough weather conditions.

UK Prime Minister Boris Johnson has extended his condolence to the families of the victims.

“My thoughts are with the loved ones of those who tragically lost their lives in the Channel today. We have offered the French authorities every support as they investigate this terrible incident and will do all we can to crack down on the ruthless criminal gangs who prey on vulnerable people by facilitating these dangerous journeys.”