ELIZABETH CITY, N.C. -- Four prisoners are now charged with two counts of first degree murder for the two prison employees killed in last week’s prison escape attempt at Pasquotank Correctional Institution in Elizabeth City.

Pasquotank County Sheriff Randy Cartwright said Friday the men were behind last week's failed breakout from Pasquotank Correctional Institution, which was the deadliest escape attempt in state prison history.

Correctional officer Justin Smith and vocational worker Veronica Darden were killed after the inmates set a fire inside a prison sewing plant and apparently planned to climb over prison fences. 

Cartwright said two other employees of the prison in Elizabeth City remain in critical condition, so more charges are possible. The sheriff said last week that those hurt mostly suffered stabbing or slashing wounds.

Accused of murder are 28-year-old Mikel Brady, 29-year-old Wisezah Buckman, 30-year-old Jonathan Monk and 33-year-old Seth Frazier.

Brady was convicted of shooting a trooper in the face in Durham in 2013.

Smith and Darden will be laid to rest this weekend.