AURORA, Colo. -- Firefighters are monitoring an apartment building for gases in an effort to determine what chemicals one of its residents might have used to booby trap the place -- in case the materials go off, authorities said Friday.
The resident, James Eagen Holmes, 24, is the suspect in a mass shooting early Friday at a movie theater about four miles away.
"It's a pretty extensive booby trap. We're not sure what it's attached to. There are trip wires. There are three containers and we don't know what's inside," said Chris Henderson, deputy Aurora fire chief.
If there is a detonation that causes a fire, firefighters will fight it from the outside of the building, he said.
The building and several around it have been evacuated.
Kaitlyn Fonzi, 20, a graduate student at University Hospital, said she lives in the apartment below that of the suspect.
About midnight, Fonzi said she heard music that was techno-like, with a deep reverberating bass coming from that apartment. She went upstairs to the suspect's place and put her hand on the door handle. She felt it was unlocked, but she didn't know if he was there and decided not to confront him.
"I yelled out and told him I was going to call the cops and went back to my apartment," she said.
Fonzi called police, who told her they were busy with a shooting and did not have time to respond to a noise disturbance. She said she was surprised to learn later that the apartment was booby trapped and was shaken by the news.
"I'm concerned if I had opened the door, I would have set it off," she said.
Fonzi said she had seen the man one or two times before but never talked with him.
She said she believes the music was on a timer because it started about the time of the shootings.
Police have searched apartments and broken out windows at the building, but Fonzi said she doesn't know the condition of her apartment or car.
When asked about plans to possibly try to detonate the device with a robot, she said, "It's not ideal situation, but if that has to be done to keep safe, then it has to be done."
University of Colorado pharmacy student Ben Lung, 27, who lives two floors down from the suspect, said he and other residents were evacuated around 2 a.m. by SWAT officers armed with rifles.