STILLWATER — Officials have placed Stillwater state prison on lockdown after an inmate attacked a corrections officer.

The state Department of Corrections says a prisoner targeted the sergeant in a living unit late Wednesday morning. Department spokeswoman Sarah Fitzgerald says corrections officers responded quickly and contained the incident.

According to a press release, the officer was checked at a hospital and released. Fitzgerald says the prison will remain locked down while the incident is investigated.

Last year assaults inside Minnesota prisons led to the deaths of two corrections employees and injuries to more than a dozen others. In July, an inmate allegedly beat officer Joseph Gomm to death with a hammer at Stillwater prison.

The union representing corrections officers is urging the Legislature to hire 327 more officers.