The Maharashtra government has ordered a probe by experts.
A "big spark" in the electricity pole providing power to the girder launcher preceded its collapse during the construction of a viaduct for the Samruddhi Expressway in Maharashtra's Thane district a day ago, in which at least 20 persons were killed, police said on Wednesday.
The incident occurred sometime after Monday midnight at Sarlambe village in Shahapur tehsil, around 80 km from Mumbai, they said.
Hours later, the police registered an offence against Navayuga Engineering company in connection with the incident in which 20 persons, including 10 labourers, were crushed to death and three others injured, an official said.
The girder launcher along with a segment launcher (crane), weighing 700 tons, came crashing down from a height of 35 metres, the Maharashtra State Road Development Corporation (MSRDC) earlier said.
The incident occurred during the construction of a 2.28 km-long viaduct by Navayuga Engineering and VSL India Private Limited, Singapore, it said.
One of the injured labourers, identified as 33-year-old Premprakash Ayoddha, lodged a complaint in this connection.
The complainant works for VSL Pvt Ltd company, which was given the sub-contract by Navayuga Engineering company for the girder launcher, police said.
"Based on Ayoddha's complaint, the Thane district rural police on Tuesday registered an offence against Navayuga Engineering Company, which was given the task of installing the girders for the viaduct on the Samruddhi Expressway," a police official said citing the first information report (FIR).
In his complaint, Ayoddha said that on July 31, he reported for duty at 8 pm. Around 18 labourers, 8 to 10 engineers and some supervisors were present at the spot at that time.
"We were working on a girder launcher machine around 11 pm. Suddenly there was a big spark on the electricity pole providing power to the girder launcher, due to which we fell down along with the machine (girder launcher). Some of my colleagues and I were trapped under it," the complainant said in the FIR.
Hearing the cries of the victims, other workers and people residing nearby came to the spot and launched the rescue work, he said.
The complainant alleged that mishap was a result of the negligence of the local contractors appointed by the companies given the task of installing girders.
An FIR was registered against Navayuga Engineering under Indian Penal Code (IPC) sections 304-A, (causing death by negligence), 337 (causing hurt by act endangering life or personal safety of others), 34 (common intention) and others, police said, adding that further investigation is on.
A total of 28 persons were working at the site when the girder launcher crashed. Five of them remained unhurt, the MSRDC has said.
The Maharashtra government has ordered a probe by experts.
The 'Samruddhi Mahamarg', named Hindu Hrudaysamrat Balasaheb Thackeray Maharashtra Samruddhi Mahamarg, is a 701-km-long expressway connecting Mumbai and Nagpur.
It passes through ten districts: Nagpur, Washim, Wardha, Ahmednagar, Buldhana, Aurangabad, Amravati, Jalna, Nashik and Thane.
The construction of a 600-km long stretch is completed and opened for traffic, while the work of remaining 101 km-long stretch between Nashik and Thane is in progress.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)