The family of a Walmart employee in Illinois who died from complications of COVID-19 filed a wrongful death lawsuit Monday, alleging the retailer knew about the man's symptoms and disregarded them.

Wando Evans, 51, died March 25. He was a 15-year employee of Walmart who worked as an overnight stock and maintenance associate at a store in Evergreen Park, which is near Chicago, according to the lawsuit.

Evans told store managers about his symptoms, but was ignored, the lawsuit, which was filed in Cook County said. The store sent him home from work on March 23 and he was found dead in his home two days later, the lawsuit said.

It alleged the retailer knew other employees — in addition to Evans — were showing signs of the coronavirus, too. It said that another man who worked at the store died on March 29.

In a statement Monday, Walmart said the company is "heartbroken at the passing of two associates at our Evergreen Park store and we are mourning along with their families."

The lawsuit alleges Walmart was negligent because it did not adequately clean the store, enforce social distancing, notify employees about colleagues who were showing coronavirus symptoms and provide protective gear, such as gloves and masks.

The retailer said it deep-cleaned the store, even though the two employees had not been there in more than a week. It said it also hired a company to clean the store and had a third-party and a health department inspect it.

Walmart said it has also increased safety measures across the company by adding sneeze guards at cash registers, putting decals on the floors about social distancing and limiting the number of customers in stores.

"We take this issue seriously and will respond with the court once we have been served with the complaint," it said.

The family's attorney, Tony S. Kalogerakos, said Evans' brother, Toney Evans, tried to contact store managers and Walmart's corporate offices to cover burial expenses through a emergency relief fund for employees. He said Wando's brother did not get an answer and decided to file the lawsuit after learning about the working conditions of the store.

Walmart, the largest private employer in the U.S., has seen a surge in sales as customers have stocked up on food, cleaning products and paper goods. The retailer announced on March 19 that it would give bonuses to full- and part-time employees and hire 150,000 new workers to keep up with that increased demand.

As coronavirus cases increase in the U.S., Walmart has announced new measures to keep customers and employees safe. Walmart reduced store hours in mid-March to allow more time for restocking and cleaning. It announced last week that it will limit the number of customers in stores, provide gloves and masks to employees, and take employees' temperatures when they report to work.

—CNBC's Dan Mangan contributed to this report.