Police have identified the gunman who opened fire on a crowded Colorado movie theater as 24-year-old medical student James Holmes.
At least 12 people were killed and dozens more were wounded when Holmes opened fire on the audience of a midnight showing of "The Dark Knight Rises" in the Denver suburb of Aurora.
Survivors say Holmes entered the theater through an emergency exit, tossed some sort of tear gas canister into the crowd, and then opened fire.
Holmes was arrested shortly after the attack in the parking lot of the theater.
Police say his nearby apartment was "booby-trapped" with several explosive devices that they're still working to defuse.
Five buildings have been evacuated while they carry out that work.
The FBI says there are no known terrorist links to the massacre.
Sources say Holmes was studying neuroscience at the University of Colorado until last month, when he withdrew from the school.