BARACK Obama said the horror of the cinema shootings had hit him hard because his two young daughters could easily have been in the audience.

The US President broke off campaigning for November's election to send his sympathies to the families of the dead and those injured in the shootings at the Century 16 complex in Aurora, Colorada.

President Obama said his daughters Malia, 14, and 11-year-old Sasha were keen film-goers, and that his heart went out to the victims and their families.

He led the condolences in the US, ordering the Stars and Stripes flag to be at half-mast over the White House where he hurriedly returned from a campaign trip to Fort Myers, Florida.

Mr Obama told supporters: "There are going to be other days for politics. This, I think, is a day for prayer and reflection." He then asked them to join him in a moment of silence to commemorate the victims of the shooting.

"I'm sure many of you are parents who had the same reaction I did when we heard the news. My daughters go to the movies. What if Malia and Sasha had been at the theatre, as so many kids do each day?

"I hope all of you will keep the people of Aurora in your hearts and minds today. May the Lord bring them comfort and healing in hard days to come."

Like Mr Obama, Mitt Romney, his Republican challenger, pulled his campaign from Colorado and cancelled a speech as the rivals declared a truce out of respect for those killed in the shooting.

Speaking in New Hampshire, Mr Romney said: "Our hearts break with the sadness of this unspeakable tragedy."

US flags will be flown at half-mast on all public buildings, including the White House, for six days.

It was unclear last night whether the President plans to visit the scene.

The Queen sent her "heartfelt sympathy" to President Obama after the shooting.

Her message said: "I was saddened to learn of the tragic loss of life earlier today in Denver, Colorado.

"Prince Philip joins me in extending our heartfelt sympathy to you and the people of America at this time.

"My thoughts and prayers are with the families of those killed and I wish the many who were injured a swift and full recovery."

British actor Gary Oldman was the first of the stars of The Dark Knight Rises to react to the Batman massacre, when he offered his "deepest sympathies" to the victims' families.

Oldman said in a statement: "My prayers and deepest sympathies are with the victims and their families of this horrific act."

The film's director, Christopher Nolan, actress Anne Hathaway, and its star Christian Bale are all in France for its Paris premiere, which has now been cancelled.

Chiefs at Warner Bros studio, who pulled the red carpet premiere, released a statement expressing their shock at what happened.

Bale's Twitter site and those of other Batman stars, such as Michael Caine, had not been updated to reflect the tragedy.

Meanwhile, Steve Hogan, the Mayor of Aurora, said the city had "taken a blow" but would get back on its feet.

Speaking last night, Mayor Hogan said: "It is an absolute horror for all these people who were in these theatres and for their families. Our hearts go out to them."

In New York, Mayor Michael Bloomberg called on Mr Obama and Mr Romney to tell the public what they would do to reduce gun violence.

The Mayor is the billionaire backer of Mayors Against Illegal Guns, a coalition of city leaders advocating stricter rules on gun sales and ownership,

Mr Bloomberg said: "Soothing words are nice, but maybe it's time that the two people who want to be President of the United States stand up and tell us what they are going to do about it, because this is obviously a problem across the country.

"I don't think there's any other developed country in the world that has remotely the problem we have. We have more guns than people in this country."

Michael Hancock, the Mayor of Denver, said: "Our hearts are broken but we are determined to move forward together."