The Colorado shooting claimed the lives of 12 people. It seems to be a lone man's shooting spree at a Colorado theatre screening "Dark Knight Rises" early on Friday. News media outlets later picked up that one of the victims at the shooting was a survivor of the Eaton Centre shooting almost two months ago.

Gunfire and an explosive device being set off were reported at the Aurora theatre on the outskirts of Denver. Police received calls about the shooting about 12:30am Friday local time from witnesses at the scene.

Police chief Dan Oates said 50 others were wounded in the incident. One person had been arrested and police found no evidence of other shooters.

"Witnesses tell us he released some sort of canister. They heard a hissing sound and some gas emerged and the gunman opened fire," Chief Oates said.

NBC News reported the shooting suspect's name is James Holmes.

Holmes, 24, allegedly threw some type of gas or explosive device and started shooting at the front of one of the theaters. Police noted he was wearing a bulletproof vest.

Below are messages posted to Twitter by those moved by the shocking incident.

@EcheMadubuike: R.I.P to all of the victims of the Colorado #Theatershooting. Let's continue to pray for the victims. #RT to show RESPECT.

@samtwomiller: "the streets of heaven are too crowded with angels." #theatershooting

@whoisvers: #ThingsIWontForget The poor lives lost in the #TheaterShooting .. RIP

@jjamesduffyy: Thoughts and prayers go out to the victims and families of the shooting in Colorado. RT to show your respect. #theatershooting

@TheScottyAdams: Innocent lives were lost because of a senseless act of violence. Prayers go out to the victims and families #theatershooting

News and updates on the tragic incident are also tweeted to keep Twitter users informed.

An update from 9NEWS Denver said one of the victims in the theater shooting was a survivor of the Eaton Centre mall shooting in Toronto seven weeks ago.

‏@ABCWorldNews: Just In: The suspected gunman in the Colorado shooting told authorities he was the joker, according to one police official. #theatershooting

@abc7: #TheaterShooting Suspect J Holmes was University of Colorado PhD student but withdrew in June. He graduated from UC Riverside in 2010.

@9NEWS: Aurora #theatershooting victim Jessica Ghawi recently survived Toronto mall shooting. Blogged about her experience: [link]