Guards are force-feeding at least 16 of the 84 prisoners who are refusing to eat. Officials said five of the men have been hospitalized, but they do not have life-threatening conditions.
The hunger strike began in February with a few prisoners who were protesting conditions and their indefinite confinement at the U.S. military base in Cuba.
The strike grew over the past week after a clash between guards and prisoners. There are 166 men being held at the prison.
The Associated Press contributed to this report.