A disgruntled ex-employee pulled out a container of gasoline, poured it around the office and then lit a fire before fleeing, the company's CEO said. View Full Caption DNAinfo/Erica Demarest

CHICAGO — A disgruntled ex-employee threatened his former boss before setting the office of Deliver My Grub on fire Friday, seriously injuring a female employee, according to the CEO of the company.

Deliver My Grub, which has an office in Avondale and delivers restaurant items to customers, let the employee go about two months ago, CEO Jimmy Griggs said. At the time, the employee had refused to accept back pay, Griggs said, but he later demanded it so Griggs was working with lawyers to sort it out.

The employee called Griggs on Friday afternoon and threatened him, saying he wanted his money in 24 hours or Griggs "would see what was going to happen," Griggs said.

About an hour after the phone call, at 4:35 p.m., the man walked into Deliver My Grub's office at 3058 W. Belmont Ave. and began knocking over furniture, Griggs said. A staff member tried to stop the man, at which point the ex-employee pulled out a container of gasoline, poured it around the office and then lit a fire before fleeing, Griggs said, citing reports from his employees.

A 45-year-old woman who works at Deliver My Grub slipped in the gasoline and became "engulfed in flames," sustaining serious injuries to her legs and lower body, Griggs said. He said another employee pushed the woman out of the flames.

Officer Jose Estrada, Chicago Police spokesman, said the woman was taken to Advocate Illinois Masonic Medical Center in serious condition.

Griggs, who spoke to DNAinfo Chicago while driving to the hospital to visit his employee, said she is in "good spirits" and that he was told she is past the point of risk from her burns. He has not been able to visit the office to see how badly it was damaged, he said.

Deliver My Grub is open for business since it uses Web-based technology, but Griggs said his "whole staff is shaken up."

"I'm just thankful that everyone's alive," Griggs said, adding that he wants the ex-employee to be apprehended.

Police are still searching for the ex-employee and charges have not yet been filed, Estrada said.

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