Bishop David Monroe, 69, is recovering in hospital. (Roman Catholic Diocese of Kamloops)

One person is in custody after the Roman Catholic bishop of Kamloops, B.C., was severely beaten at the city's cathedral.

RCMP were called to the Sacred Heart Cathedral in the B.C. Interior city on Friday night, and found Bishop David Monroe bleeding on the floor of the church rectory. Police believe he had been beaten with a blunt object.

Monroe, 69, was rushed to hospital, along with another priest who dislocated a shoulder trying to fend off the attacker.

"We pray for the bishop and for the conversion of the guy who hurt the bishop," said Rev. Derrick Cameron. "Certainly, he [Monroe] could have died if we weren't there. Timing-wise, he would have bled to death."

The assailant fled the church, but police say they tracked down the suspect.

"We started backtracking to see what else had gone on in the evening, and one thing that did catch our eye was that a couple hours previous there was an adult male that was brought to the Kamloops hospital by some family members who were concerned for his mental health," said RCMP Staff Sgt. Garry Kerr. "They said his mental state was quite deteriorated and he was apparently having some delusions of some sort involving religion."

Kerr said police found the man in a shed at his father's home on the north shore of Kamloops. It appears he swam across the Thompson River.

Monroe, who has been bishop since 2002 of the 155,000-square-kilometre central B.C. diocese, was taken to hospital with what Kerr described as serious injuries. He was expected to be released Saturday.

"I was at the hospital [Friday] night and was able to speak … very, very briefly with the bishop.... The most severe injuries the bishop had were all above the neck and face and [he was] severely, severely beaten," Kerr said.

"We are fortunate, quite frankly, that it was not a double murder … I mean, the scene was that horrific, and I am just glad to say that he [the suspect] is in custody."

The suspect, whose name has not been released, was undergoing a psychological evaluation. He was scheduled to appear in a Kamloops court on Monday.