MADISON, Wis. -- Four people were injured in a building explosion and partial collapse on Madison's west side Tuesday evening, the city's fire department said.
The explosion, which happened around 5:55 p.m. near the corner of Gammon Road and Park Ridge Drive, caused extensive damage to multiple units of a condominium complex and blew out doors and windows of surrounding homes.
First responders took one person to a hospital, and three others went to hospitals on their own with minor injuries, Madison Fire Chief Chris Carbon said during a news conference at the scene around 7:45 p.m.
The city's Heavy Urban Rescue Team also responded to the scene to shore up the building so crews can do a second search inside. That process, Carbon said, will be slow and methodical.
First responders do not have evidence anyone is trapped inside the building and have not received reports of missing residents, he added.
In total, at least six units in the complex were affected, but the entire building has been deemed at least temporarily uninhabitable. The fire department and American Red Cross are working with those displaced to meet any immediate needs they may have.
Fire officials have not yet determined what caused the blast.
Gammon Road reopened to traffic early Wednesday morning.
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Witnesses reported hearing an explosion nearby, and one witness said she saw multiple people with apparent injuries.
Neighbor Gail Rychlowski said at first, she thought the loud noise she heard was gunfire.
"Then there was a rumbling, and stuff just exploded off of all my walls," she said. "My shelves, my knick-knacks, everything."
Smelling gas, Rychlowski quickly evacuated her home.