The mishap occurred at the Civil Hospital campus in Kharsia town in the district.
"Banshidhar Rathia (35) and Samaru Yadav (45) were killed when the part of the two-storeyed structure, which was being demolished, caved in," Raigarh SP Anand Chhabra said, adding the debris fell on the onlookers there.
Six persons, who were trapped under the rubble, were shifted to hospital where Rathia and Yadav were declared brought dead.
The district health department was building doctors' quarters by pulling down the old structure in the hospital campus.