An inmate serving time for homicide killed a corrections officer Wednesday afternoon in Stillwater prison, marking the first such death of an on-duty Minnesota prison guard.

The attack occurred about 1:30 p.m. in an industry building and prompted a temporary lockdown of all state prisons, according to the state Department of Corrections.

Officer Joseph B. Gomm, who had celebrated 16 years on the job Tuesday, was taken to Regions Hospital in St. Paul, where he died of his injuries.

“Joseph gave the ultimate sacrifice while working to protect the citizens of Minnesota,” said Corrections Commissioner Tom Roy, who declined to name the attacker.

A relative identified the inmate as Edward Muhammad Johnson, who is serving a nearly 29-year sentence for second-degree murder. After Wednesday’s assault, he was transferred to Oak Park Heights, the state’s only Level 5 maximum-security prison.

In a news conference, Roy said a weapon was used to kill the 45-year-old officer from Blaine. He did not disclose the type of weapon, but sources told the Star Tribune that Gomm was stabbed before being bludgeoned with a hammer.

Edward Muhammad Johnson

Johnson, 42, was convicted in 2003 of stabbing his roommate, 22-year-old paralegal Brooke Thompson, to death while her 5-year-old daughter was nearby.

His parents, both Chicago police officers, died in a 1988 murder-suicide. Johnson was 12 when he watched his father shoot his mother eight times in their home shortly after she filed for divorce, according to the Chicago Tribune.

On Wednesday, other officers were close by when Gomm was attacked.

At least two ambulances raced to the prison’s south gate, according to emergency dispatch audio. Personnel at one point intubated the officer before he was placed into an ambulance and driven to Regions.

The assault took place in one of the prison’s large industry buildings, where offenders take welding and carpentry classes. “Those work assignments are considered a privilege,” Roy said.

Gomm, like most guards, was armed only with pepper spray and a radio. Firearms are typically reserved for officers stationed in watch towers and assigned to crisis response teams, Roy said.

More than 1,600 inmates are housed at the 104-year-old prison, 527 of them sentenced for homicide. Prisoners on average have three prior felonies and 10 prior gross-misdemeanor histories.

Roy described Stillwater as a “flagship institution” that houses a significant population of offenders with mental illness and chemical dependency. “Erratic behavior is not uncommon,” he said.

Since the killing, counselors and clergy have been supporting prison personnel, Roy said. DOC employees were sent to the hospital to be with Gomm’s grieving relatives.

“The corrections family is reeling from this incident,” Roy said. “We are not accustomed to losing staff.”

Among those mourning Gomm’s death was officer Theresa Herberg-Dunn, who wrote on Facebook, “He worked in my unit for years and made sure I got out safely to see my loved ones every day. I never let a day go by where I didn’t thank him for that!”

In a statement, Gov. Mark Dayton said, “I am appalled at the horrific murder of Officer Joseph Gomm. … We are all indebted to the courageous corrections officers and other state employees who risk their safety in Minnesota’s prisons to ensure the safety of their colleagues, our communities, and the inmates themselves.”

DOC staffing levels have slightly increased in recent years, Roy said, but subsequent requests for additional funding at the Legislature “did not come to fruition.” An analysis by the National Institute of Corrections concluded that the agency was short-staffed by about 150 people.

DOC spokeswoman Sarah Fitzgerald said the guard’s death “is the first in the state as far as we can verify through our records.”

Jeff Beahen, president of the Minnesota Law Enforcement Memorial Association, said Gomm’s death is a reminder that unarmed prison guards may face more risks than police officers who are “afforded the luxury of being armed.”

“This really shows how dangerous the correctional officer job can be,” Beahen said.

A cell house at Stillwater prison is pictured in this file photo.

Beahen, who also acts as Rogers’ police chief, has offered Gomm’s family a full line-of-duty funeral — a procession that typically includes bagpipes and attracts up to 2,000 officers from across the state.

Three weeks ago, an Oak Park Heights corrections officer was seriously injured during an altercation that threw the facility into lockdown. The officer fought back and was assisted by other guards. The offender is serving a life sentence for aiding and abetting second-degree murder. Charges have yet to be filed in that case, according to the Washington County Attorney’s Office.

Earlier this year at Oak Park Heights, several staff members were injured during two fights in the span of a few days. Ten staff members were seen at the hospital and released.

“Our officers interact with offenders every day,” Roy said. “I think it’s fair to say the relationships are significant. Offenders know officers, and officers know offenders … and those relationships often keep people safe.”

Staff writer Matt DeLong contributed to this report.