(Portage, WI) -- One of the country's most notorious serial killers is dead.

Wisconsin prison official say Jeffrey Dahmer was attacked and killed in a state prison today. A spokesman says Dahmer had massive head injuries and was pronounced dead en route to a hospital.

A second inmate was also attacked with Dahmer in a prison recreation area. That inmate is hospitalized.

Dahmer was serving a life-without-parole prison sentence for killing at least 16 young men.

Police made a grisly discovery when they arrested Dahmer in 1991 -- skulls and other body parts hidden in his Milwaukee apartment.

Dahmer told investigators he picked up young men and boys at gay bars, shopping malls, and other places, lured them back to his home and strangled and dismembered them.