A teenager is believed to have been among the four people who died when a migrant boat capsized in the Channel.
Kent County Council leader Roger Gough told a council meeting on Thursday a youngster was one of the fatalities.
He told councillors that 12 of the 39 people rescued from the freezing water on Wednesday were lone migrant children who have now been taken into the authority’s care.
The tragedy, he reportedly said, was a “sobering reminder of the human costs of what is an ongoing crisis”.
Drones were being used to scan the water for anyone unaccounted for as the search in the Channel continued, with ships asked to post lookouts.
Meanwhile, the Marine Accident Investigation Branch (MAIB) reviewed evidence of the incident to decide whether an inquiry should be launched.
The major rescue operation off the Kent coast began at 2.16am on Wednesday after reports of a boat in distress, and involved the Royal Navy, French navy, Coastguard, RNLI lifeboats, ambulance service and police.
A fishing boat was first on the scene, arriving at 3.04am, and was one of three to help in the rescue, the Government said.
The RNLI’s Simon Ling said the scenes faced by arriving lifeboat crews were “harrowing”.
Speaking at the Dungeness lifeboat station, the charity’s head of lifeboats said: “The fishing boats were already on the scene but it’s fair to say the crews arrived to quite a distressing and harrowing situation with persons in the water in varying levels of distress.”
The incident was “hugely traumatic” for all involved and lifeboat crews had to get those rescued “out of the water as quickly as possible” and “deal with various states including being very cold and hypothermic”, he said.
“Ahead of any investigation or review of what happened, it’s fair to say that the fishing boat and the actions of its crew undoubtedly saved countless lives, and the RNLI would very much want to recognise that,” Mr Ling added.
Two casualties were taken to the William Harvey Hospital in Ashford, bosses there said.
One was later discharged but the other had died by the time they arrived, it is understood.
The Ministry of Defence (MoD) said 401 migrants were detected in eight boats on Wednesday, not including those who died.
The latest figures take the provisional total for the number of migrants who have made the crossing so far this year to 45,223.
A Government spokesman said: “Overnight and today the search continues with aerial assets to ensure that everyone is accounted for.
“HM Coastguard have been broadcasting to all shipping requesting that they post lookouts on board their vessels and report any sightings to Dover Coastguard.”
The MAIB said: “We are in the process of gathering information about the incident as part of the process of conducting a preliminary assessment.
“A decision on whether an investigation will be launched will be made once the evidence has been reviewed.”
