The suspect in the mass shooting at an Aurora, Colorado, movie theater screening of the new Batman film early Friday had colored his hair red and told police he was "the Joker," according to a federal law enforcement source with detailed knowledge of the investigation.

At least 12 people were killed in the rampage and 58 were injured, one fewer than earlier reported. Of those injured "nearly everyone was shot," Aurora Police Chief Dan Oates said Friday night, adding that a handful of people were hurt in the resulting chaos.

Ten of the victims were killed inside the theater while two others died at hospitals. As of Friday evening, the 10 bodies had been removed from the complex and authorities were preparing to begin "the agonizing process" of notifying families, Oates said.

A mug shot of suspect James E. Holmes has not been released. Witnesses to the shooting described him as wearing a gas mask that concealed much of his face and head. But the federal law enforcement source's information about the suspect's appearance fits with a statement from New York Police Commissioner Ray Kelly, who was briefed by Colorado authorities Friday.

Oates declined to comment on Holmes' appearance other than to describe what he was wearing, and said he would not release his booking photo "for investigative reasons."

The Joker has long been a fixture in Batman comics and was famously brought to life by the late Heath Ledger in 2008's "The Dark Knight," the predecessor to Friday's release of "The Dark Knight Rises." Ledger won a posthumous Academy Award for his sinister portrayal of the iconic villain who encourages anarchists to take over Gotham City.

Meanwhile, authorities were faced with the difficult task of entering Holmes' Aurora apartment, which was left rigged with traps.

"It's booby-trapped with various incendiary and chemical devices and trip wires," Oates said, adding that it could take days to work through the apartment safely.

Five buildings around the apartment building were evacuated, Oates said. Residents were allowed back home briefly Friday night to retrieve such emergency items as medicine.

Authorities have postponed until Saturday any attempts to enter the apartment and are bringing in resources from the federal government to help with the situation, Oates said.