12 PEOPLE KILLED, 50 INJURED IN DENVER MOVIE THEATER SHOOTING LOS ANGELES, July 20 （Xi

12 PEOPLE KILLED, 50 INJURED IN DENVER MOVIE THEATER SHOOTING LOS ANGELES, July 20 (Xinhua) -- A masked gunman released tear gas and opened fire into a crowded movie theater in a suburb of Denver early Friday, killing 12 people and injuring at least 50 others, police said. Aurora Police Chief Dan Oates told reporters that the shooter, aged 24, had been arrested in the parking lot behind the theater. The FBI said there was so far no indication of any links to terror groups. Some moviegoers said they thought the attack was part of the show when they saw a person appearing at the front of the theater during the movie, pointing a gun at the crowd. Police and firefighters rushed to the mall shortly after the shootings occurred at around 12:30 a.m. local time (0630 GMT). CNN reported at least 20 people were being treated for gunshot wounds in hospital, three of them in serious condition.

1. In the shooting, 50 people were killed and 12 people were injured.()

2. The shooter was arrested.()

3. The FBI said that the shooter was from the terror groups.()

4. The moviegoers didn’t realize the person would shoot at the crowd at first.()

5. Only the police went to the mall to help.()

请帮忙给出正确答案和分析，谢谢！