Three of the four inmates injured in a fight Tuesday at the Iowa State Penitentiary in Fort Madison are serving time for First-Degree Murder. The Iowa Department of Corrections has identified the inmates as Derek Smith, Toby Michael, Heath Burgess and Joshua George.

Smith, Michael and George are all incarcerated for crimes that include murder, while Burgess is in prison for robbery and sex abuse convictions. All four inmates were assigned to a program in which they pre-build houses for Habitat for Humanity. Corrections department spokesperson Fred Scaletta says the four men were in the Habitat for Humanity work area Tuesday at 11:30 a.m. when they became involved in a fight.

All four suffered stab wounds and three remain hospitalized. The incident remains under investigation and the prison is under lockdown.