Indian police on Friday detained five officials from the company building an overpass that collapsed in the eastern city of Kolkata, killing at least 23 people and injuring dozens more.
"Five people of the Hyderabad company have been detained for questioning," said Kolkata deputy commissioner of police Akhilesh Chaturvedi, referring to the contractor IVCRL.
He gave no further details, but police earlier said they had registered a case of culpable homicide against the firm, whose offices in Kolkata have been sealed by investigators.
Derek O'Brien, a state lawmaker, said the company had been blacklisted in other states and had a "bad reputation"
Ninety people were saved after a 100-meter length of the overpass broke off at one end and slammed into pedestrians and vehicles below on a road through a busy commercial district near Girish Park in the eastern city on Thursday. Many of them suffered serious injuries.
Rescuers worked all night using saws and small cranes to dig through the wreckage in search of survivors.
"It is being ensured that there are no more dead bodies under the debris," S.S. Guleria, a deputy inspector general of the National Disaster Response Force, told Reuters.
A police official said the rescue teams will keep working.
"The rescue operation will not stop until all the blocks of concrete and iron girders have been cleared," said deputy police commissioner Akhilesh Chaturvedi.
Indian company IVRCL was building the 2-km (1.2-mile) Vivekananda Road flyover. Its shares closed down 5 percent after falling by up to 11.8 percent on news of the disaster.
"We did not use any inferior quality material and we will cooperate with the investigators," the company's director of operations, A.G.K. Murthy told reporters on Thursday. "We are in a state of shock."
The state government, which is fighting for re-election in a vote that starts on Monday, pledged to take action against those found responsible.
But the tragedy has already turned into a blame game, with the opposition accusing the Mamata Banerjee state government of being responsible.
"It is an act of fraud protected by the state government," Bharatiya Janata Party vice president and Minister for State and Minority Affairs Mukhtar Abbas Naqvi told reporters.
A newspaper reported last November that Banerjee wanted the flyover - already five years overdue - to be completed by February. Project engineers expressed concerns over whether this would be possible, the Telegraph newspaper said at the time.
Years of delays may have caused corrosion to metal elements of the flyover, undermining its stability, according to rescuers who examined the wreckage. Locals said that concrete was poured on the stretch the night before its collapse.
A senior IVRCL manager had drawn national condemnation for calling the disaster an "act of God."
A coordinated rescue operation was slow to get under way, with access for heavy lifting gear and ambulances restricted by the buildings on either side of the flyover and heavy traffic.
Eyewitness Ravindra Kumar Gupta, a grocer, pulled out six bodies with the help of friends.
"Every night, hundreds of labourers would build the flyover and they would cook and sleep near the site by day," said Gupta.
"The government wanted to complete the flyover before the elections and the labourers were working on a tight deadline ... Maybe the hasty construction led to the collapse."
Video footage aired on TV channels showed two auto rickshaws and a crowd of people suddenly obliterated by a mass of falling concrete that narrowly missed cars crawling in a traffic jam.
Yogesh Sharma was sitting at a small roadside tea stand with friends when the overpass, which spanned nearly the width of the city street and was designed to ease traffic through the densely crowded neighbourhood, "came down with a huge crashing sound."
"I left my cup of tea and ran," said Sharma, a 23-year-old resident of the Bara Bazaar neighbourhood. "I was crying at the spot."
"The concrete had been laid last night at this part of the bridge," resident Ramesh Kejriwal said.
"I am lucky as I was planning to go downstairs to have juice. When I was thinking about it, I saw that the bridge had collapsed."