Wayne City Manager John Zech said rescuers using search dogs found the body of salesman James Zell, 64, of neighboring Westland, in the debris left by the explosion at the store, located in downtown Wayne about 15 miles from Detroit.
Shawn Bell, Wayne's deputy fire marshal, later said workers found the body of a woman in the rubble. Her name was not immediately released. Zech had said earlier the missing woman was a clerical worker for the store in her 50s who also was from Westland.
The massive explosion about 9 a.m. reduced the William C. Franks Furniture store to a pile of wood, crumbled drywall, twisted metal and broken bits of furniture. A bureau drawer could be seen. The blast shattered windows at nearby businesses.
"It sounded like a bomb," said 47-year-old Lisa Johns, who said she was watching television in bed at her home nearby and rushed to the scene. "The power went off and came back on two or three minutes later."
Owner Paul Franks, who was pulled out shortly after the blast, was upgraded from critical to serious condition in the burn unit at the University of Michigan's medical center.
Police evacuated homes and businesses near the store. Officials expected most residents would be able to return by the end of the day, but several were offered hotel rooms for the night as a safety precaution. City officials late Wednesday declared a state of emergency in a bid for financial help for the state.
During the search, groups of firefighters entered the building four and five at a time, scraping away at the rubble using long poles with hooks on the end. Bobcats and front-loaders moved around the area. Video footage shot from TV helicopters showed dozens of rescuers working on and around the remains of the store.
Consumers Energy spokeswoman Debra Dodd said the utility believed natural gas was involved, but the cause of the blast is still unknown. The company had received a call of a possible gas leak in the area several hours earlier and a worker had been trying to track down the source when the explosion took place, Dodd said.
Shortly after the blast, from beneath the mountain of debris, flames and spewing water, Jennifer Gietzen, 36, heard yelling and saw some movement.
Her husband, Chris Gietzen, and workers from the auto shop the couple manages then ran into the remains, climbed "10 feet high on a pile of twisted everything" and started digging after finding Franks, the burned and struggling store owner.
"He was trying to pull himself out, but his leg was stuck," Chris Gietzen, 35, told The Associated Press.
Zech said Franks' father founded the high-end furniture store, which local residents said has been in business for more than 40 years. Mayor Al Haidous described the store as a "jewel" in the city.
Franks "treats everybody like family," said store delivery worker Russell Brothers, 52, who said he has worked at the store for 18 years. He wasn't scheduled to work Wednesday but came to see what happened after the explosion.
Franks' family issued a statement through the hospital expressing appreciation for the support and concern of the community.
"We are focused on his care and treatment at this time and we ask that you respect our privacy. Our concern extends to all others affected by today's tragedy," the statement said.
Zech said Zell's family also asked for privacy and planned a statement on Thursday.
A person who was driving by the store when it exploded was in stable condition at Oakwood Annapolis Hospital, hospital spokeswoman Paula Rivera-Kerr said.
Brothers and saleswoman Deanna Dow were helping authorities pinpoint where in the building the missing workers might have been when the explosion occurred.
"We're just shaken up," said Dow, who had been scheduled to start work at noon.
Chris Gietzen said the scene was treacherous, but he felt obligated to help.
"I couldn't be someone who didn't do that," said Gietzen, a reserve officer with the Wayne Police Department.
Associated Press writers Corey Williams, David Aguilar, Randi Berris and David N. Goodman in Detroit contributed to this report.