Michigan State Police said the body of a newborn was found Sunday morning in a portable bathroom at the Electric Forest music festival in Rothbury, Michigan.

Police said an employee of the portable restroom vendor discovered the body of a “neonate” — a newborn infant who is four weeks old or younger — during routine maintenance in the camping area. The festival, located at the Double JJ Resort about 64 miles northwest of Grand Rapids, opened on Thursday and ran through Sunday.

“We appreciate the public’s cooperation and ask that people avoid speculation on social media out of respect for the investigation and those affected,” Michigan State Police said in a statement.

Festival organizers addressed the death in a statement posted online Sunday night, saying they were “heartbroken.”

“It causes us so much pain to have to share this difficult news with you,” the statement read. “Michigan state police continues to investigate this tragic event, if you can assist in any way.”

The four-day festival shut down hours earlier than scheduled Sunday night because of severe weather. Organizers said the festival resumed into early Monday. The event, which blends a Robin Hood-style forest theme with psychedelic and dance music, was sold-out, according to WOODTV.

The investigation is ongoing, police said. They encouraged anyone who was in the camping area and observed anything unusual to come forward with information.