The escape by Derreck White, 25, who police said also used the name Abraham Pearson, sparked a manhunt and prompted a lockdown of the Frank Murphy Hall of Justice.
White overpowered Deputy Harrison Tolliver as he transported White and two other prisoners to a holding cell, Wayne County Sheriff Benny Napoleon said. White stabbed the deputy with a plastic comb that had been fashioned into a shank, Napoleon said.
"It was very quick," Napoleon said. "He overcame the deputy, took his clothing, got on the elevator and escaped."
Napoleon described the deputy's injuries as "puncture wounds," and said he is fine.
White was scheduled to be in court Monday morning to learn his punishment after being convicted last month of carjacking, armed robbery and firearms charges, according to court records.
Detroit police said White approached the parked minivan, threatened the woman driver and ordered her to get out. She was not injured. White drove off and was involved in a two-vehicle accident nearby, investigators said. Detroit police Chief James Craig said White abandoned the vehicle on the city's east side.
Officers put the courthouse on lockdown, which delayed the day's hearings, and searched the area near where the van was found.
The FBI and other law enforcement agencies were working with the Wayne County sheriff's department and Detroit police in the manhunt, Craig said. White was believed to be on foot because no other vehicles have been reported stolen in the area.
"We have good information that we're working on," Craig said during a late-morning update to reporters.
White may have put on the sheriff's department uniform during the escape, but Craig said it was believed he was no longer was wearing it.
White's defense attorney, James Howarth, said his client has a history of mental illness but was found competent to stand trial. He said he believes White's mental health issues may have played a role in his escape Monday.
"In his right mind he would not have done this," Howarth said. "In the year I have known him, he has never showed the slightest symptom of being dangerous. Something is very wrong."
Howarth said: "It may have been a final act of desperation if you don't want to go to prison."
The judge's office where his case was listed said it had no information to release.
People who waited outside the courthouse for hearings on Monday morning were allowed to enter a few hours after the escape.