Eyewitnesses have described seeing dead bodies, walking wounded and bleeding children after a masked gunman wearing a bulletproof vest walked into a packed theatre and opened fire on moviegoers.
The theatre in Aurora, Colorado, was full to capacity with people watching a midnight screening of the new Batman film, The Dark Knight Rises. Around 30 minutes into the screening a man hurled tear gas into the theatre and then started firing.
Aberneezer Mergia told Sky News: "As I looked around there were a couple of dead bodies and someone coughing blood. We were really scared and we just tried to get to the nearest car. We saw a police officer carrying a child. There was blood everywhere it was pretty horrific."
The scene outside the theatre in Aurora, Denver
Many people in the theatre initially thought that it was some kind of stunt that was part of the movie.
Paul Otermat, speaking to ABC News, described the initial confusion. He said: "I thought it was a promotional thing. But [the shooter] comes in and when he threw the tear gas initially and when the smoke came out from it, I knew something was wrong.
"It was really crazy, he just walked in pretty casually and just started firing."
"Then when he started firing, it was really, really loud. It was like Bam! Bam! Bam! It wasn't like rapid fire. It was just pointing and shooting.
"We saw him come in, throw tear gas and start shooting into the crowd as they exited.
"We dropped through the floor as soon as he started firing into the crowd and then we crawled out to a point where we thought he couldn't see us any more, and then we ran through the lobby and there were still shots being fired.
"We got out to the parking lot and left as quick as we could.
Moviegoers flee the scene
"[The cinema] was packed. I feel like there was only maybe seven to 10 seats open out of the whole movie theatre.
"We were lucky to be on the left side there and a fairly quick way out thereof. We were worried he was going to shoot us as we were getting to the exit.
"We dropped to the ground as soon as the shots started being fired and we crawled out and ran through the lobby and got to our car and drove off."
Too much blood & tears for one night.
— Sky Kim (@BadLil_Lady) July 20, 2012
A man speaking to Colorado's 9news told how a girl had described the gunman. He said: What she described sounded like madness. A man kicked through the door in a riot helmet with a bulletproof vest covered in all black with goggles.
"When she turned around she was slowly making his way up the stairs shooting people."
Jeremy Jojola, a journalist with Colorado's 9News spoke to these two men who were in the theatre at the time of the shooting
A teenage boy also speaking to 9news was attending the premiere with his sister and friend and were in theatre 8 next door to the theatre where the shooting started.
He said: "People were standing and going to leave. Me and my sister and my friend were wandering what was going on what was happening and at that point I saw something come through the wall objects just flew through the wall.
"People stood up and started checking themselves. A couple of people were walking away holding areas and I heard moaning like they were in pain and that's when I started to get worried.
"We didn't really know something was happening until someone came from the left entrance and told us we shouldn't go outside cause there was a guy with a gun out there."
Witnesses have described the shootings in Denver
When asked if any children had been injured he said: "A cop came through the door holding a little girl on her arms and she wasn't moving."
He added how he had overheard a girl talking to someone on the phone who said that there were bullet holes in the little girls back.
University Hospital confirms the youngest patient from #theatershooting is 3 months old
— 9NEWS Denver (@9NEWS) July 20, 2012
ABC News report that Aurora resident Brittany Jackson, was in the local emergency room when the shootings happened.
She said: "One poor guy had blood caked all over his face. He just was not responsive at all."
An Aurora police spokesman confirmed the number of casualties and added: "Most of us have never experienced anything like this before."