Gunman kills 12 people in cinema in the U.S.

Police officers outside the cinema in Denver where a masked man opened fire on those attending the premiere of Batman

A masked gunman shot dead 12 people at an exhibition of the new Batman movie at a theater in a suburb of the U.S. city of Denver, sparking pandemonium when fired tear gas into the auditorium and opened fire on the spectators. Another 50, including children, were injured in the attack during the midnight feature film "The Dark Knight Rises" in a mall in the town of Aurora, some of whom were treated for the effects of tear gas, said hospital sources.

"This is a scary fact," said Aurora Police Chief Dan Oates, in a press conference, adding that the suspect was arrested in a parking lot behind the cinema. Police said the gunman appeared in front of the screen during the movie and fired tear gas that caused screams in the film before shooting begins.

Dozens of police were dispatched to the scene of the crime, which was evacuated while they checked whether there were explosives. Authorities said there was no evidence of another gunman. Wendy Post, who was waiting to be reunited with his daughter at a local high school after the shooting, said he was told that the shooting began shortly after starting the film."He saw the door open and something was thrown in front of the screen and then the shooting started," said Post, 9News television, NBC's local partner.

President Barack Obama, who was notified of the incident on Friday morning by his homeland security adviser John Brennan, urged Americans to "stick together" with the people of Aurora in the coming hours and days. "Michelle and I are shocked and saddened by the horrible and tragic shootings in Colorado. Local and federal agents are still responding and my administration will do everything possible to support the people of Aurora in this extraordinarily difficult time," Obama said in a statement .

"As we face times of darkness and challenge, we must be together as one American family," he added. Colorado has suffered mass killings in the past. In 1999, two students opened fire at Columbine High School in suburban Littleton, near Denver, killing 12 students and a teacher.

The police spokesman Frank Fania said it was believed that the suspect was about 20 years. He had a knife, a rifle and a pistol when he was arrested and then recovered another weapon of cinema. The man wore a bulletproof vest.

"He did not resist, did not fight," he added.

Police said the building where the suspect lived was evacuated and they were looking for explosives there after the man said he had these devices at home. A witness told CNN: "We heard from 10 to 20 shots and small explosions. Shortly after that we heard people screaming. Then spoke on the PA system and said that we should all get out."

"As soon as we had people running and screaming," said the witness, adding that his friends had said the gunman wore a gas mask. A man said to the string associated with NBC that was in an adjoining room watching another function of the Batman movie when he heard shots and the theater was filled with smoke. He said he saw bullet holes in the wall and some people were injured in their room.

Fania said police received the first call alerting the shooting at 00.39 local time (0639 GMT) and answering "one or two minutes." Local hospitals were warned of a "massive casualty incident." Media reports said 10 people died at the scene and two later died at the clinic.

A spokeswoman for Swedish Medical Center in Denver said three people were admitted to hospital with gunshot wounds and were in critical condition.