FREMONT COUNTY, Colo. — An inmate assaulted theater shooter James Holmes and an officer in the Colorado State Penitentiary, the highest security prison in the state, according to the Colorado Department of Corrections Friday.

Holmes was not injured in the assault, DOC spokeswoman Adrienne Jacobson said.

Mark “Slim” Daniels, 27, will be charged with assault on a correctional officer and an assault on James Holmes, according to Jacobson.

“Daniels and Holmes are both housed at CSP. The incident occurred during an offender movement,” Jacobson said.

Jacobson said the assault took place in passing in a hallway, as Daniels allegedly lunged at Holmes and took a few swings at him.

The date and time of the assault was not confirmed, but the Denver Post reports that it took place on Oct. 8, according to a letter they received from someone claiming to be Daniels.

Holmes is currently serving 12 life sentences plus 3,318 years for murdering 12 and injuring 70 others in a shooting at the Century 16 theater in Aurora.

Daniels reportedly is serving time for menacing, auto theft, assault and smuggling contraband into prison. He was charged with first degree assault on a guard in 2006.