DENVER (CBS4)– Investigators believe an apartment fire where flames shot out of the windows was caused by a hash oil explosion. Police continue to search for one person who may have run from the burning building.

The fire broke out about 8 a.m. Thursday inside the Parliament Apartments on the 4300 block of South Quebec Street, close to the Denver Tech Center.

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(credit: CBS)

(credit: CBS)

“It sounded like booms were going off, almost like aerosol tanks were maybe blowing up,” said a witness. “It was like ‘Boom, boom.'”

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A firefighter sustained minor injuries battling the fire. Someone else was also injured and had to be taken to the hospital. That person was later taken into custody and their name hasn’t been released.

The damage is so bad it’s difficult for firefighters to collect evidence. Investigators haven’t determined that hash oil caused the explosion but butane canisters littered the balcony of the apartment where the fire started.

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More than a dozen residents were displaced during the fire. It could be another two days until the fire investigation report is complete.