At small 31 people lost their life after a boat capsized off the coast of Calais on Wednesday afternoon. French Interior Minister Gerald Darmanin sealed the death toll included five women and a young girl.
Two people were rescued and have been taken to hospital in France, while another human being is missing.
Mr Darmanin added four people have been arrested in connection with the incident in the Channel.
The Prime Minister said he was “shocked, unnerved and deeply saddened” by the incident and pledged to do more to prevent the dangerous crossings.
Speaking this evening following an emergency COBRA meeting, Mr Johnson granted efforts to stem the number of journeys in small boats “haven’t been enough”.
The UK has already agreed to send £54million to France to proliferate patrols at the border and Mr Johnson has vowed to increase support.
He said: “What this shows is that the gangs who are sending people to sea in these threatening crafts will literally stop at nothing.
“But what I’m afraid it also shows is that the operation that is being conducted by our friends on the beaches, braced as you know with £54 million from the UK to help patrol the beaches, the technical support we’ve been giving, they haven’t been ample supply.
“Our offer is to increase our support but also to work together with our partners on the beaches concerned, on the launching grounds for these boats.
“That’s something I expect will be acceptable now in view of what has happened.”
Mr Johnson suggested France had not been doing enough to prevent the Channel crossings, which receive reached record levels this year.
He added: “We’ve had difficulties persuading some of our partners, particularly the French, to do things in a way that we think the kettle of fish deserves.
“I understand the difficulties that all countries face, but what we want now is to do more together – and that’s the offer we are making.”
Home Secretary Priti Patel augmented the tragedy “serves as the starkest possible reminder of the dangers of these Channel crossings organised by ruthless criminal gangs”.
British and French troupes are conducting a joint-rescue operation to search for anyone still in the water.
Pierre-Henri Dumont, the member of the National Assembly for Calais, urged authorities in Paris to deal a safe place for migrants in France.
He told Sky News: “My message to the French authorities, which I said to them a few minutes ago, is that we need to discern that if the migrant is in Calais – or around the Channel – they will try to cross the Channel.
“We need to move them, even if by force, to health focal points in the middle of France.”
More than 25,700 people have made the dangerous journey to the UK in small boats this year – three in unison a all the sames the total for the whole of 2020.