Investigators say two propane tanks were also found at the heart of the fire, in close proximity to the pipe bomb, and the FBI is investigating the incident as a case of domestic terrorism.
The FBI released two surveillance pictures of the person of interest on Wednesday night.
The man in the picture is white with graying hair. He has a silver mustache and was wearing a dark colored cap with a light-colored log on the front. He was also wearing a gray and white horizontally striped shirt, a dark jacket with silver buttons, blue jeans and dark colored shoes.
9Wants to Know has learned evidence found at the scene has been traced back to the Target store across the street. Investigators were interviewing witnesses at the Target.
The fire started at 11:52 a.m. Wednesday in the hallway near the food court, according to West Metro Fire Department. They say the fire was contained by 11:59 a.m. and didn't spread outside the food court area. Authorities say a suspicious device, which turned out to be two propane tanks, was found in the area of the fire.
Authorities are investigating whether the propane tanks started the fire.
Around 5 p.m., authorities announced they found a pipe bomb. The bomb squad was going to detonate it, but it fell apart when investigators picked it up.
Authorities say since the FBI is involved, any suspect arrested in connection with the case will face federal charges.
The Jefferson County Sheriff's Office says the Bureau of Alcohol, Tobacco and Firearms, along with five police dogs, searched the mall for anything else suspicious. The Jefferson County Bomb Squad was also called to the scene.
"We were going to use the bomb robot to move the pipe bomb from the area where we found it, but when that device was picked up, it fell apart," Jacki Kelley with the Jefferson County Sheriff's Office said.
But Kelley says it appears the bombs were real.
"It appears as though all of the technology was there for this device to work," she said. "I don't know if these devices were meant to go off together, simultaneously... I just don't know."
Firefighters say there is no damage from the fire, but one security guard was treated for smoke inhalation.
Kelley says about 300 employees were evacuated from the mall. She says there are, on average, 6,000 to 10,000 people are in the mall around noon everyday.
The pipe bomb and propane tanks were found on the anniversary of the Columbine High School shootings, something that investigators are taking into consideration.
"It's disturbing, to say the least, that we're dealing with any other incident on a day like today. It's a date that's hard to ignore. The comparison between what happened there [Columbine] 12 years ago and having something here today, it's hard to ignore. So it's something that we'll certainly look at. But it's devastating that someone would, anyone would decide today's the day to do anything like this at all." Kelley said. "We have no idea what the relationship could be between what happened here today at the mall and 12 years ago, but it's significant to us."
Kelley says investigators are going to examine the tanks closely.
"I can tell you quite honestly that propane can be devastating," she said. "The propane tanks could have been devastating if they worked."
Kelley says investigators are looking at surveillance video from the mall and there are a lot of resources at the mall to "do everything we can" to make sure the scene is safe and there are no more devices, and then to investigate the case. She says there is a lot of video to look at.
"Hopefully that will shed some light and answer some questions for us," she said.
Deputies say customers and employees will be allowed back into the building when crews determine the mall is safe. Investigators searched the mall for most of Wednesday afternoon and Wednesday evening and determined there were no more devices inside.
Kelley says school buses were brought to the mall to take employees out of the area. She says one person from each store stayed behind in case authorities need to enter a store, but the mall will not reopen on Wednesday night. It was unclear if it would reopen on Thursday.
Lynn Setzer from Jeffco Public Schools says 25 schools were on lockout as a precaution.
"Schools were put on lockout as a precaution and because of a suspicious device that was found in the area of the fire at Southwest Plaza," Setzer said.
Lockout means there is only one point of access to each school.
Anyone with information about the incident is asked to call a tip line at 303-271-5615.
(KUSA-TV © 2011 Multimedia Holdings Corporation)