The Edmonton Institution maximum-security prison is still partially locked down after an inmate was attacked on New Year's Day.

The 44-year-old prisoner was jumped by several inmates in the gymnasium, said Rick Dhym, spokesman for Corrections Canada. The man was sent to the Royal Alexandra Hospital with a serious head injury.

"He had some surgery yesterday. He's recovering and should be back in the institution in a day or two," Dhym said Friday.

Dyhm did not identify the victim or the suspects, and did not release a motive for the attack, which was recorded by security video.

Police are investigating and Corrections Canada will conduct its own review.

The prison, known as the Max, houses 230 male offenders.