Here's an update on what we know about the Colorado theater shootings

President Barack Obama and Vice President Joe Biden meet with senior advisors in the Oval Office to discuss the shootings in Aurora, Colorado, July 20, 2012. Pictured, from left, are: Kathryn Ruemmler, Counsel to the President, and FBI Director Robert Mueller. (Official White House Photo by Pete Souza) Police are holding James Eagan Holmes in the killing of 12 and injuring of 59 in a movie multiplex in Aurora, Colorado, a suburb of 325,000 east of Denver. Patrons were in the packed theater for a midnight premiere of the new Batman movie, The Dark Knight Rises. A 6-year-old girl was among the dead and nine of the injured were in critical condition. Holmes is said not to be cooperating with authorities. He was arrested in behind the theater just a couple of minutes after a 911 call was answered. Authorities say he will be arraigned on Monday.

Authorities say Holmes bought a ticket to the movie, then left through an exit door that he propped open. He removed body armor and three firearms from a car in the parking lot and returned to carry out his carnage.

' The Aurora police chief, Dan Oates, announced at a press conference at noon Mountain Time that one of the 71 victims was struck by a bullet that penetrated the wall between two theaters in the multiplex.

' The Aurora police, perhaps together with other law enforcement officials, will hold another press conference at 7 PM MT.

' It is believed, police said, that Holmes acted alone. But they are closely cooperating with federal authorities as the investigation continues.

' The four firearms recovered by police were two .40-caliber Glock pistols (one of which was found in a car parked in a lot behind back of the theater), a Remington 12-gauge shotgun, and a Smith & Wesson .223-caliber AR-15-style rifle, the semi-automatic civilian version of the military's M-16. The Associated Press has reported Holmes had a "drum" magazine for the AR-15. These can hold as many as 100 rounds.

' The firearms were all purchased legally and recently at local stores in May, June and July. Holmes also carried at least two explosive canisters of an unknown, irritating gas that he set off in the theater before opening fire. He wore a gas mask, a ballistic helmet, a bullet-resistant vest, and leg, groin and throat protectors.

' Holmes set a timer to turn on loud music in his Aurora apartment. That music was triggered at midnight, according to what a nearby resident told reporters. Authorities say the apartment was rigged with trip wires designed to set off incendiary and chemical weapons. Investigators evacuated the building. As this post was being published, the devices had not yet been defused.

' In a report on the victims (one sailor and two airmen were injured) the Department of Defense reported: "We can also confirm that the alleged gunman in this incident, James Holmes, is not a past or current member of any branch or component of the U.S. Armed Forces."

' Speaking at a Friday afternoon press conference, University of California-Riverside chancellor Timothy White said James Holmes, the suspected shooter in the deadly Aurora, Colo. massacre, had a distinguished academic career at the school.

'He was an honor student,' White said. 'So academically he was at the top of the top. He distinguished himself from an academic point of view during his four years with us graduating with highest honors.'

' New York City Police Commissioner Raymond Kelly said: "It clearly looks like a deranged individual. He has his hair painted red. He said he was the Joker, obviously the enemy of Batman." Aurora Police Chief Oates would not confirm this, but said he had he had spoken to Kelly. Oates used to work with Kelly in New York. Federal authorities have also informed CNN Holmes had colored his hair.

' Here is an aerial map of the theater and surrounding area.