Court sheriffs quickly subdued the alleged attacker even before RCMP arrived.
Const. Lesley Smith, a spokeswoman for the RCMP, did not identify the 40-year-old suspect or the victim but said the Crown prosecutor suffered non-life-threatening injuries and was taken to hospital.
The incident started before hearings began for the day when a man was spotted wandering the halls, said a court worker.
"He was going crazy," said Kelly Penner, who had recently arrived for work at the court. "He was calling everyone names in the courthouse and yelling profanities and then walked out of the courthouse and he happened to meet (the Crown) across the street."
Penner said the prosecutor appeared to be semi-conscious and was bleeding when paramedics arrived.
Smith said the victim was punched in the face.
"Witnesses advise that comments were made by the male suspect that make us believe it was a targeted attack," she said, adding that the suspect is now being held at the RCMP detachment and is facing several charges, including aggravated assault.
Smith said the RCMP first received a call from a local men's shelter at about 8:20 a.m. Thursday, and witnesses advised police that a man was being violent towards staff members but had left the area.
Ten minutes later, police received another call about an attack on the front steps of the courthouse, where sheriffs had a man in custody, said Smith.
She did not know why the suspect was at the courthouse.
B.C. Crown Prosecutors' spokesman Neil MacKenzie said it appeared the alleged assault may have occurred during an incidental encounter outside the courthouse.
"There's some indication the suspect may have recognized the prosecutor involved, but right now we can't say definitively whether or not the prosecutor was assaulted because of who he is or his occupation."
Smith said while she has heard of threats against Crown prosecutors and defence lawyers, assaults against lawyers in Prince George are rare.
"In my six years of being in the Prince George detachment I have not heard of a Crown counsel being assaulted," she said.
-- By Keven Drews and Terri Theodore in Vancouver.