Houston Fire Department emergency responders were called to Food Town on W. Sam Houston Parkway South at Elmsworth Drive around 2:15pm.
Customers and employees huddles outside as firefighters in HazMat suits rushed into the building.
"They told us, 'everybody drop everything you got and get out of the store now, right now,'" customer James Green said.
"It smelled like strong, strong ammonia and I was like, 'wow,'" said Pamela Jordan, whose mother was evacuated.
According to HFD, some sort of refrigerant started leaking out of a cooling system on the second floor. The chemical was contained to the second floor and officials say there was no danger of it leaking outside.
"It's refrigeration equipment. It supplies the coolers and the freezers of the grocery store with all that meat and frozen foods and dairy," HFD Deputy Chief Terry Stone said.
Stone says two employees who had been working with the equipment had to be taken to the hospital.
"One of them that was still conscious was having difficulty breathing," he said. "The other one was unconscious but still breathing, so he wasn't telling us anything."
A third employee was hurt while evacuating. We were there as medics treated her and then took her away in an ambulance.
"She's pregnant, nine months now," the woman's husband, Ibrahim Davoh, said. "So, right now, she's not feeling good. She cannot even breathe."
Firefighters and HazMat crews disposed of the refrigerant and employees returned to work around 4:15pm. The store re-opened about an hour later.
HFD is working to determine how the leak happened. Food Town managers declined to comment. We will keep you updated on Eyewitness News and abc13.com.