A building under construction collapsed in northern Illinois on Robert BrownMonday, toppling three cranes and injuring the workers operating them.

The collapse happened around 2 p.m. in Machesney Park, according to John Bergeron, chief of the Harlem Roscoe Fire Protection District.

"They were up in some cranes doing some work," Bergeron said during a news conference. "All three cranes came down ... The whole structure collapsed."

The building is owned by machine company Hennig Inc., which did not respond to USA TODAY's request for comment.

Crane operators' conditions remain unknown

Bergeron said two of the workers were taken to the hospital and the other refused treatment. All three operators are men in their 30s and the fire chief did not know the condition of the two who are hospitalized.

The collapse of the building caused steel and beams to come down and damage several vehicles at the construction site, according to NBC Chicago. All three cranes were 30 to 40 feet up in the air before they toppled over, the outlet said, citing officials.

The Occupational Health and Safety Administration (OSHA) will take charge of the investigation, the fire chief said. The construction site remained secure until OSHA arrived, according to Bergeron.