The Gurgaon Police said the incident occurred around 7.30 am and three labourers sustained injuries. They were discharged from a hospital after treatment, officials said.
The NHAI said it has suspended key personnel of developer Larsen & Toubro and supervision consultant AECOM following the incident.
Built in four packages, the length of the expressway is 29 kilometres. Of this, 18.9 km falls in Haryana, while the remaining is in Delhi.