A 21-year-old man who apparently suffers from a mental illness stabbed a man in the back several times at the Wendy’s restaurant in Sunny Isle, St. Croix, on Sunday afternoon, according to V.I. Police spokesman Toby Derima.

Derima told The Daily News on Monday that charges against Andres Ponce Jr. of Bethlehem Village housing community have been upgraded to first-degree assault.

Ponce was also charged with carrying or using a dangerous weapon during the commission of a crime of violence.

The incident occurred at around 3:15 p.m. Sunday.

Derima said investigators found that Ponce approached an older man from behind and stabbed him several times in his shoulder and back. A family member who was with Ponce stopped the attack and he was detained by an off-duty police officer who was nearby.

The victim was transported to the Luis Hospital for treatment.

Derima said Ponce “is reported to suffer from mental illness.”

He was unable to post $25,000 bail and was remanded to the custody of the Bureau of Corrections pending his advice-of-rights hearing. That hearing was delayed Monday because of a network outage on St. Croix, and he is scheduled to appear in court today.

— Contact Suzanne Carlson at 340-714-9122 or email scarlson@dailynews.vi.