LAKEWOOD, Colo. (CBS4) – Firefighters responded to a large fire at an apartment complex at West Jewell Avenue and Sheridan Boulevard Friday night.

Four people were injured in the fire and two had to be hospitalized. Two others refused to be treated at the scene. It’s not clear what types of injuries the people sustained.

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Both the Denver Fire Department and the West Metro Fire Department battled the blaze that was reported just after 8 p.m. Within 5 minutes the fire had exploded. Fire officials said just after 9 p.m. it was considered under control.

The fire was concentrated on the third floor and involved 24 units.

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“I hear the ambulance, someone knocks on my door, firefighter, and this has never happened so I ran outside, hyperventilating, saw the smoke,” resident Lynsey Dietz said.

“When they got here they made a coordinated fire attack,” Div. Chief Clint Fey with West Metro Fire said. “They primarily found two fire units on the third floor that were heavily involved in fire. They concentrated their efforts on that fire, keeping that fire from spreading.”

The cause of the fire is under investigation and fire officials say it looks suspicious because the fire became aggressive so fast.

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The Red Cross worked with displaced residents to help them find a place to go for the night.