By 7 p.m. Monday, six hours after a half-built downtown structure partially collapsed with construction workers inside, firefighters had removed four injured people from the site at 4th and Race street and begun chipping away at concrete in hopes of extricating a fifth.

Their mission had changed by 7:45, according to an email sent from City Manager Patrick Duhaney to members of City Council. It was no longer a search and rescue. It was a search and recovery.

"It goes without saying that this is a horrible tragedy," Duhaney wrote in the email. "Our thoughts are with the family of all those affected, particularly the individual who has not yet been found. We are all praying for a miracle."

His wording echoed what Hamilton County Coroner Lakshmi Sammarco told reporters in a news conference at 7. Although rumors of the fifth worker's death had circulated since shortly after the collapse, she did not confirm them.

"They're hoping for a miracle," she said instead, referring to the firefighters. "We're hoping for a miracle. We are preparing for not, unfortunately, and I think it's just going to be a while before we have anymore answers."

Fire Chief Roy Winston said crews would continue the search overnight.

Cincinnati Fire and Urban Search and Rescue Teams from all over the state work into the night in search of a victim at the building collapse on 4th Street. They use advanced tools and extreme will power to accomplish their mission. pic.twitter.com/sgWGidRVkB — Cincy Fire & EMS (@CincyFireEMS) November 26, 2019

Exactly what happened here?

Workers were constructing a planned $44 million mixed-use development meant to include a parking garage, retail space and apartments when complete. The project is the brainchild of 3CDC, which had employed Turner Construction as a contractor and Baker Concrete as a sub-contractor to get the job done.

The collapse happened around 1:15, according to police. According to a statement from 3CDC, workers had been pouring concrete from the unfinished seventh floor to the sixth below when part of the structure gave out. Three were quickly transported to hospitals: Two to the University of Cincinnati Medical Center and one to Christ Hospital.

A 10 p.m. statement from Turner Construction said all three had been treated and released from various hospitals without incident. The statement also mentioned a fourth injured worker — also treated and also released by 10 — for the first time.

The fifth remained missing at midnight.

A building collapse sounds serious. How is it going to affect my week?

The collapse closed 4th Street between Vine Street and Central Avenue as well as Elm Street from 3rd to 5th Streets. Those roads could potentially remain closed through the weekend, police said.

Are the companies involved liable for the workers' injuries?

Baker Concrete corporate counsel and spokesman Rich Farr said Monday it was too early to tell what contributed to the collapse, and his company’s primary concern “is the well-being of any injured co-workers."

Baker has been involved in a number of high-profile construction projects in Cincinnati, including Great American Tower, for which it poured two million cubic feet of concrete. OSHA records show Baker has had no Cincinnati-area workplace safety violations since 2015. However, in that time, OSHA cited and fined the company for what it called "serious violations" in Texas, Colorado, New York, Oklahoma and Florida.

Richard Miller, head of the University of Cincinnati's College of Engineering and Applied Sciences, said Monday night he believed the search for answers and culpability could potentially take years.

"Depending on the circumstance, it may take a few days to a couple of weeks for the investigators to get all their data," he said. "And then it can take months or years before any sort of final result is published."