The collapse happened at around 9 a.m. at the Coda Kitchen and Bar on Maplewood Avenue. 

Police identified the victim as 50-year-old Guo Tai Chen. 

Authorities say four people were inside the building at the time of the incident. Workers were building an internal staircase from the kitchen to the basement when something caused it to collapse.

Two men were trapped in the debris. Chen died at the scene. An injured construction worker was freed by police who entered the building without protective gear. He was taken to University Hospital in serious condition. A third construction worker and a restaurant manager were uninjured. 

"Our hearts go out to the families," says Mayor Victor DeLuca. "This was a person who went to work today expecting to come home tonight, and they're not going to be there."

Investigators will try to determine whether the improvements had anything to do with the collapse. "Proper permits were taken," DeLuca says. "There was an inspection on May 28. Everything was in order."

Several fire department and rescue units were called the scene. The units were working to secure the structure.