An investigation has been launched after U.K. parents Kris Thompson and Iboyla Adam found their 22-month-old toddler Hailey dead in her bedroom just hours after she was sent home from the hospital, according to The Independent. The parents, from the city of Wigan, have accused medical professionals of not taking their daughter’s health seriously enough after she was diagnosed with a virus on a Dec. 18 hospital visit, where she was allegedly prescribed fluids and paracetamol. She was found unresponsive in her bed the next day, and died soon after being rushed to an emergency room, according to the outlet.

“We can’t believe we have lost our little girl. It all happened so quickly. Something in her body took control of her,” Kris Thompson said. “It was a horrible sight and will haunt me for the rest of my life.” A spokesperson for Wrightington, Wigan and Leigh NHS Foundation Trust told The Independent, “Our sincere condolences go out to Hailey’s family at this tragic time. We are aware of the family’s concerns and are currently awaiting further information to understand more.”