Two convicted killers took a counselor and a teacher hostage at knifepoint Thursday in the library of Northern State Prison, authorities said.

Police were trying to negotiate with the inmates, and an assault team of prison guards was standing by."We have not heard any demands at this point," said James Stabile, spokesman for the state Department of Corrections. "There's been some discussion back and forth but the more intensive negotiation hasn't begun."

It wasn't immediately clear whether there were others in the library when the two women were taken hostage. Stabile said that as far as he knew, the women were not injured.