Officials said that the incident occurred when a dumper truck tried to cross the bridge near Wadhwan tehsil, even though the entry of heavy vehicles to the bride was restricted.
A total of 26 worker were present at the site during the tragic incident. A rescue team of 38 Battalion, Border Security Force, Sakawrtuichhun (Aizawl) reached the spot with the medical team and tracker dogs at the site upon receiving information.
The National Disaster Relief Force and Quick Response Team have recovered 18 bodies so far and rescued three injured after an under-construction railway bridge collapsed in Mizoram's Aizwal district.
Due to heavy rains in Himachal Pradesh, Dharamshala-Shimla National Highway 88 was not operational for movement of vehicles as a small bridge collapsed on Wednesday morning near Jawalamukhi.
"The bridge girder process was duly approved by IIT experts. A high-level inquiry committee has also been constituted to investigate the matter," railway officials said.