Police investigating the London bombings have no idea whether the terrorists responsible have fled abroad, died in the explosions, or are planning further atrocities, they admitted last night.
Metropolitan Police Commissioner Sir Ian Blair said all options were being considered but there was "no evidence whatsoever" to support speculation an Islamic terror cell in the Midlands may have been responsible.
The confirmed death toll rose to 49 last night, but more bodies are trapped at the blast-hit tube train in Russell Square.
Another 22 people were in a serious or critical condition in hospital.
London was picking up the pieces after the four bomb attacks which injured 700 after three underground trains and one central London bus were targeted.
Some workers stayed at home and, although much of the tube system was operating, trains were much emptier than usual.
Charles Clarke, the Home Secretary, said it was too early to be sure who was responsible for the blasts, but said there was "a strong possibility" it was al Qaida or a linked group.
Sir Ian, the head of the Metropolitan Police, said the bombings bore "all the hallmarks of al Qaida".
He warned "it was likely" that a terrorist cell could still be active.
The commissioner said: "This is a national issue, not just for London. All of the police forces in the UK are taking steps to increase their footsteps on the ground and to work with communities."
But he admitted: "They are either at large in the UK or abroad or they are dead, I don?t know which one of those it is."
Sir Ian described reports that the bombers came from the Midlands as "pure speculation".
Police have refused to comment on reports that they are hunting the radical Muslim cleric Mohammed al Garbuzi, a Moroccan who vanished from his home in north London last year.
Meanwhile, faith leaders including Christians and Muslims put on a display of unity in Birmingham.
The Most Rev Vincent Nichols, the Roman Catholic Archbishop of Birmingham, joined other faith leaders at the city's Central Mosque to offer support to the Muslim community.
The archbishop met Dr Mohammed Naseem, the mosque's chairman, along with Rabbi Leonard Tann, from Singers Hill Synagogue, and the Very Rev Gordon Mursell, Dean of St Philip's Anglican Cathedral in Birmingham.
The Muslim Council of Britain said it "utterly condemns" the attacks.
Distraught relatives descended on central London, looking for missing loved ones, with some handed out photographs, or stuck posters on lamp-posts.
But there were also tales of individual heroism.
Former fireman Paul Dadge, from Cannock, Staffordshire, gave first aid to victims of the Underground explosion between King's Cross and Russell Square.
He said: "I was trained in first aid when I was in the fire service but to be honest I think it was instinct more than training that took over. I always seem to be in the wrong place at the right time." He insisted he was "not a hero".
Members of the royal family visited a number of hospitals treating the injured, including the Queen, who sent a defiant message to the terrorists behind the London bombings.
She said: "Those who perpetrate these brutal acts against innocent people should know that they will not change our way of life.
"Atrocities such as these simply reinforce our sense of community, our humanity and our trust in the rule of law. That is the clear message from us all."