Allen Marshall spent Wednesday and Thursday at an Exxon station near the Detroit Medical Center with a sign that said "FREE GAS FOR NURSES."
"I just love them and I want them to know that," he told CNN affiliate WDIV.
Michigan is one of the hardest-hit states in the coronavirus pandemic, according to Johns Hopkins University, with 10,791 cases and 417 deaths.
Imran Al Samet works at the station and told CNN that Marshall had bought gas for between 50 and 80 people on Wednesday and Thursday morning.
"There's a lot coming through," he said at about 11 a.m. on Thursday.
Most of the nurses aren't coming inside the store, so he hasn't heard their reactions, but people were excited.
"They're happy with it," he said.
Marshall told The Detroit Free Press that he'd been saving the money to buy a knife-sharpening tool. His wife is an essential worker at Blue Cross Blue Shield, the paper reported, so he did the giveaway after he dropped her off at work.
"Oh my goodness, that is so nice of him," one nurse, who wasn't identified, told WDIV. "That's so good. God bless him."
When the money ran out, Marshall flipped his sign, which on the back read, "THANK YOU FOR ALL YOU DO!!!" He waved to passing first responders and essential workers.
A woman identified only as Alana told WDIV that she heard about Marshall's good deed and decided to come help. She said her nephew is a nurse.
"It just kills me every day to know that he's going to work. I don't know if he could get sick or what's going to happen," she said. "They're heroes and we need to do what we can to support them."
She bought another $200 worth of gas and can even be seen via CNN affiliate WDIV's video pumping it for some of the nurses.