Gunman kills 12 in Colorado movie theater NEW: Police revise estimate of number wounded to 38 NEW: Officers find "items of interest" in suspect's home, law enforcement source says Shooter used an "AK type" rifle and two handguns, a law enforcement official says (CNN) -- A heavily armed gunman tossed tear gas into the darkness of an Aurora, Colorado movie theater Friday and then sprayed the audience with gunfire during an early morning screening of the new Batman movie, killing 12 and wounding 38 others, authorities said. One of the injured was just 3 months old, according to hospital workers. The suspect was not immediately identified. Police said he was a man in his 20s from Aurora. President Barack Obama said he and first lady Michelle Obama were "shocked and saddened" by the shooting and pledged the administration's support for victims of the shooting. Police said the gunman "appeared" in the front of the theater and threw a smoke bomb before opening fire. A federal law enforcement official told CNN the smoke bomb described by witnesses was tear gas. It was unclear how the man got into the theater, but witnesses told CNN affiliate KUSA that he came in through an emergency door. Officers rushed many of the wounded to hospitals in their patrol cars. The shooter used at least four guns -- an "AK type" rifle, a shotgun and two handguns, the federal law enforcement official told CNN. Law-enforcement officers who searched the the suspect's apartment found "items of interest," a federal law enforcement source involved in the investigation told HLN. He did not elaborate. A woman who lives across the street from where the suspect is believed to live said her building had been evacuated by police around 4 a.m. They told us there was a bomb or bomb material located in the house across the street from us. Rebecca Bradshaw said. In addition to looking into the possibilty of explosives, ATF agents also are conducting emergency traces on the weapons used to see how they were obtained, Mangan said. Police initially said 14 people had died -- 10 in the theater and four at area hospitals, but revised the death toll to 12 later Friday morning, according to Lanigan. Several people remained in critical condition at area hospitals, however. The victims being treated there ranged in age from 3 months to 45, the hospital said. Denver Health Center had six patients from the shooting, one of them in critical condition, five in fair, said Shelly Davis, house supervisor. Swedish Health Center spokeswoman Nicole Williams said her hospital was treating three people, two of them in critical and one in fair condition. A fourth patient was on the way, she said. Parker Adventist Hospital was treating two people for minor injuries, according to a spokeswoman. Share your story with us on CNN iReport. CNN's Ed Payne, Joe Sterling, Tina Burnside, Mike Brooks and Jim Spellman contributed to this report.