London - British Prime Minister Theresa May called an emergency national security meeting on Friday after the Bastille Day attack in the French city of Nice, in which at least 84 people were killed.May, who was due later on Friday in Scotland, said she had asked her deputy national security adviser to chair the COBRA emergencies committee, which groups top ministers and security chiefs.The meeting was aimed at reviewing "what we know and what we can do to help", she said in a statement, expressing shock over the "horrifying attack".A government spokesperson said there had been a "small number of injured" British nationals.May took office on Wednesday after David Cameron stepped down as premier after Britain's shock June 23 vote to leave the European Union."We must work with France and our partners around the world to stand up for our values and for our freedom," she said."If, as we fear, this was a terrorist attack then we must redouble our efforts to defeat these brutal murderers who want to destroy our way of life," she added.Her assurances of cross-Channel co-operation echoed remarks by Foreign Secretary Boris Johnson, who campaigned for Britain to end its 43-year period in the European fold.Voicing shock at the "appalling" assault, Johnson, who was the star guest at the French ambassador to London's Bastille Day party on Thursday, told the BBC that terror "represents a continuing threat to us in the whole of Europe and we must meet it together".Meanwhile, London Mayor Sadiq Khan said he was reassessing security levels in the capital."We will be reviewing our own safety measures in light of this attack," he said.Expressing solidarity with the French, he added: "Londoners today stand united with Nice and all of France in our grief."They will not win. Not in France, not in London, not anywhere."While Paris and Brussels have both suffered devastating jihadist attacks in the past year, Britain has been spared a major assault since the July 2005 bombings in London's public transport system.After the November attacks in Paris, in which 130 people were killed, English football fans attending an England-France match memorably sang the French national anthem to show solidarity with their neighbours.