The Hudson County Prosecutor’s Office is investigating the death of a sheriff's officer who fell from the ninth-floor window of the Hudson County Administration Building in Jersey City.

The officer was identified as 29-year-old Officer Justin Rivera, who worked for the Hudson County Sheriff's Office under Sheriff Frank Schillari.

The prosecutor's office says they were notified around 9:30 a.m. Friday that someone had fallen from the top floor window of the courthouse.

Witness, Steve Roosen happened to be walking by.

"I thought maybe it was a person falling off of maybe like a scaffolding or something along those lines,” he said.

Another witness Eleni Vittas told News 12, "There were a lot of people. I asked somebody to call the police."

Rivera, who was on duty at the time of the incident, was taken to Jersey City Medical Center and pronounced dead around 10 a.m. Officials say the cause of death was accidental but the circumstances leading up to it are still being investigated.

"Just surreal, unfortunate, sad, unnerving just to see that happen," said Roosen.

Sheriff Frank Schillari calls this one of the saddest and most horrific days his department has experienced.

"Justin Rivera was a great young officer who exemplified the highest ideals of integrity, compassion and professionalism. He is lost to us all but he will never be forgotten,” Schillari wrote.

The sheriff called Rivera an excellent officer and an outstanding young man.

The courthouse was not open to the public on Friday, due to a power outage which officials say was unrelated to Rivera’s death.