GUWAHATI/AIZAWL: At least 23 construction workers from West Bengal's Malda, including six of a family, died and three others were wounded when the gantry of a 100-metre-tall rail bridge being built in Mizoram collapsed on Wednesday morning at a site 21km from the state capital Aizawl.The search for an unspecified number of workers reported missing was suspended after sundown because of the difficult terrain and the possibility of rain, state disaster management and rehabilitation minister Lalchamliana told TOI."We have retrieved 18 bodies so far.

The search for the rest and the missing workers will resume on Thursday," he said.Two members of a local quick-reaction team deployed by the state government rescued an injured engineer stuck atop one of the piers by rappelling down the structure over the Kurung river, officials said.The accident site near Sairang, the last railhead in the northeastern hill state, is part of a 51.3km route originating at Bairabi on the Assam-Mizoram border and an extension of a national project to connect the capitals of eight northeastern states by rail.Northeast Frontier Railway's CPRO Sabyasachi De said an inquiry had been instituted to find the reasons and fix accountability for the collapse of the rail bridge, whose technical feasibility had been verified by IIT Guwahati.'Incident due to collapse of gantry launched on bridge' The bridge sagging incident in Mizoram which has claimed 17 lives was due to the collapse of a gantry which was being launched on the under-construction bridge over Kurung river, the Railways said Wednesday.

The Railways has constituted a high-level committee to probe the incident involving the under-construction bridge, one of the 130 bridges in the Bhairavi-Sairang New Railway Line project.A Railways spokesperson said the gantry which collapsed was designed by STUP Consultant and proof checked by IIT Guwahati.

"High level enquiry committee has been constituted to probe into the matter," he said.

Gantries are heavy steel structures used to lift and support bridge segments or girders as they are placed while being supported by the bridge piers instead of the ground."The bridge did not collapse.

It was a gantry which fell while it was being launched on the under-construction bridge," the spokesperson told PTI.

While Mizoram CM Zoramthanga referred to the incident as a bridge collapse, the Railways claimed that the part of the bridge which has already been constructed is still intact.

The Bairabi-Sairang line is a 51 km long from Bairabi to Sairang under the Northeast Frontier Railway zone of Indian Railways.

The rail line entails 130 bridges, 23 tunnels and four stations -- Hortoki, Kawnpui, Mualkhang and Sairang.