The Harris County Sheriff's Office said deputies responded to reports of a burglary at the fast-food restaurant in the 600 block of FM 1960 West at about 3 a.m.
Deputies said they found two men inside the building wearing ski masks and dark colored clothing. One of the burglary suspects was detained, but the other had allegedly barricaded himself inside the restaurant, HCSO said.
In an 11 a.m. press conference, HCSO Major Earl Dean said that the second suspect "fled upstairs into the attic area, where we are still actively searching for the suspect."
However, just minutes later, a spokesperson with the sheriff's office told ABC13 that law enforcement had exhausted the possibility of the suspect still being inside the Burger King after several hours. The spokesperson said they believe that the suspect may have escaped earlier when deputies first arrived, but they are talking to the first suspect to get more information.
"Right now, we believe they came in through forced entry through the drive-thru window," Dean added. "That's still preliminary."
ABC13's SkyEye crew was on the scene of the investigation. They spotted what's known as a "Rook" at the entrance of the restaurant. It's a modified caterpillar skid steer, or digger, created by Ring Power Corporation.
"We got law enforcement hiding behind their vehicles, trying to stay in a safe space. That's why they use the drones and the robots... for the safety of the officers," SkyEye reporter Tammy Rose said. "As well as using that rook. A couple of years ago, we saw one of those in action, breaking down like an entire home to get somebody out of the house safely."
READ MORE: Meet 'The Rook,' the SWAT vehicle instrumental in ending tense standoff in Humble
Alex Ramsey, who pilots SkyEye, has a background in law enforcement and gave insight into what may happen next.
"As time does go on and time gets pressed, they will start deploying CS (tear) gas inside as an irritant to try and get him to come out. Situations like that," Ramsey said. "Last case scenario would be physically going inside the building and extracting him out."
During ABC13's 24/7 streaming newscast, several moments of movement could be seen from outside. At one point, a fog-like substance, presumed to be tear gas, was seen inside the building, with officers moving swiftly on one side of the eatery.
Officials said they only recovered some burglary tools but were treating the situation as if the suspect was barricaded and armed.
Deputies are continuing to canvass the surrounding area for any additional clues.