The mishap yesterday was triggered when a huge scaffolding at the site collapsed trapping workers in the rubble.
"Six workers were pulled from the rubble and have been transported to area hospitals. The injuries as non life- threatening, but significant," Houston Fire Department (HFD) Captain Ruy Lozano said.
"It was like an explosion but not too hard. It sounds like something is cracking, but a lot...And I could see it coming down that fast," a witness said.
The accident occurred at an under-construction luxury apartment building at 300 Crawford, Commerce, near Minute Maid Park, officials said.
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"We are monitoring the situation very closely and working alongside authorities as we try to determine the cause of this accident.
"In the meantime, we are grateful to the first responders on the scene and praying that everyone is OK, The Finger Companies, which owns the building," said in a statement.
HFD units arrived on the scene within three minutes of the report. HFD had more than 30 units on scene including several heavy rescue units.
Occupational Safety Health Administration (OSHA) inspectors will be in charge of the investigation and will ultimately determine what caused the collapse.