A masked, heavily armed gunman killed at least 12 people and wounded 38 more -- including a 6-year-old girl -- during an early Friday morning screening of The Dark Knight Rises at Century 16 Theater in Aurora, Colorado's Town Center Mall, police chief Dan Oates told reporters July 20.
Police arrested the shooter in the theater's rear parking lot. The man -- whose identity has yet to be revealed -- is believed to be in his early 20s.
"He did not resist. He did not put up a fight," police spokesman Frank Fania tells CNN. Police seized the man's rifle and handgun, according to Fania, and another gun was found in the theater.
The gunman's home and car being searched for possible explosive materials or devices. Police also are conducting emergency traces on the weapons used to see how they were obtained.
According to CNN affiliate KUSA, the gunman kicked in an emergency exit door and tossed a canister of tear gas into the theater before opening fire. "We just heard a pop, pop, pop, pop," Quentin Caldwell, who was attending a Dark Knight Rises screening in an adjacent theater, recalled.
Of the wounded, at least 20 are being treated at the University of Colorado Hospital, according to spokeswoman Jacque Montgomery. "They're arriving by police, by ambulance," she told CNN. "Some are walking in." Ten people were killed in the theater and another two died at area hospitals, Oates added; early reports suggested 14 people had been killed and 50 had been injured.
President Barack Obama, 50, issued a statement Friday saying he and First Lady Michelle Obama, 48, were "shocked and saddened" by the mass shooting. "As we do when confronted by moments of darkness and challenge, we must now come together as one American family."