Firefighters made a grisly discovery at an abandoned Philadelphia building on Wednesday when they discovered human remains after putting out a fire in an abandoned building.

Authorities were alerted at about 7 p.m. about a fire at an abandoned building along the 2200 block of South Street. 6ABC reports that structure was once home to a Thai restaurant that has been closed for several years.

After the fire was extinguished, fire crews found human remains in a shallow grave dug into the floor of the basement. The body appeared to have been bound, police said.

The medical examiner’s office is working to identify the man and determine his cause of death.

The incident is being investigated as a homicide.