A strong thunderstorm swept eastern and northeastern parts of Bihar on Friday night, shattering an under-construction bridge over the Ganga, damaging houses, uprooting trees and electricity supply lines and killing at least four people in different districts.

India Meteorological Department, Patna, scientist Anand Shankar said the speed of the storm was 40 to 50km per hour.

As the gale touched the under-construction 3.2km-long bridge, being built at a cost of Rs 1,711 crore over the Ganga between Bhagalpur and Khagaria districts, parts of it collapsed at Sultanganj.

The bridge is supposed to be completed by December this year, and is in the last leg of its construction.

Officials of S.P. Singla Constructions Private Limited — the company that is building the bridge — told media persons that the structure suffered damage worth at least Rs 40 crore after segments of the span on both sides of a pillar was damaged in the strong winds and fell down.

The four-lane bridge is an ambitious project of Nitish Kumar’s government. Its foundation stone was laid in February 2014. After construction, the bridge will link National Highways 31 and 107, benefitting several districts.

Sultanganj Janata Dal United MLA Lalit Narayan Mandal alleged corruption and irregularities in the construction of the bridge and called for a thorough probe into it.

“Poor quality materials have been used in the bridge. There has been much corruption in its construction. This is the reason behind the structure being unable to withstand a normal thunderstorm. I had asked the government officials and the private company involved in the construction of the bridge to ensure quality, but it fell on deaf ears,” Mandal told reporters after inspecting the site and the extent of damage.

The MLA also revealed that he informed chief minister Nitish Kumar about the incident and sought an investigation into the matter.

Bhagalpur divisional commissioner Dayanidhan Pandey told The Telegraph that he had “talked to the district magistrate about the bridge incident. There have been no casualties, though some damage has happened. The managing director (MD) of Bihar Rajya Pul Nirman Nigam Limited (BRPNNL) has visited the spot and will take appropriate decisions regarding any probe or investigation.”

When contacted, BRPNNL MD Sanjay Kumar Singh told this newspaper that a probe committee comprising experts from National Institute of Technology (NIT) Patna has been formed.