A number of cars and bodies are still under the rubble of the bridge that collapsed in Miami, US, yesterday.
Workers are slowly breaking up chunks of a newly built footbridge that collapsed on to a major road, killing at least six people.
Authorities say more victims could be found in crushed vehicles in the rubble.
The 950-ton bridge plummeted on to traffic on one of the busiest roads in South Florida on Thursday.
With at least eight vehicles still buried, the death toll could rise, said Juan Perez, the Miami-Dade Police Department director.
"We know that there's people missing, the family members know that there's people missing, and what we can tell them is that we can assume that they're in there," Perez said.
According to Perez, after searching the site with sniffer dogs, police determined no one would be pulled out alive.
The victims have not been publicly identified, but at least one was a student at Florida International University, which borders the roadway, officials told the news conference.
Reuters reports that at least 10 people were taken to hospitals; two were in critical condition.
Witnesses told local media the vehicles had stopped at a traffic light when the bridge collapsed on top of them about 1.30pm local time.
Uncertainty over the stability of remaining sections of the bridge hampered rescue efforts, officials said.
It was too early to say whether criminal charges might be brought against anyone.
The 53-metre-long bridge connected the university with the city of Sweetwater and was installed in six hours on Saturday over the eight-lane highway, according to a report posted on the university's website.