Three took overdoses of prescription medicine they had apparently been hoarding, and the fourth tried to hang himself, said Cmdr. Robert Durand, a detention camp spokesman. None of the suicide attempts succeeded, he said.

"At this point, I have no idea of motive, no idea of any co-ordination and no idea of any intended message," Durand said.

The attempted hanging took place in a medium-security camp where prisoners live in groups of up to 10 men in long bays lined with metal cots. When guards entered the unit, roommates

"tried to prevent them from rescuing the detainee by using fans, light fixtures and other items as improvised weapons," Durand said.

Guards halted the attempted hanging, quelled the disturbance and moved the roommates to a maximum-security area, Durand said.

The three who took overdoses were treated with activated charcoal to absorb and neutralize the medications, and two were held for observation in the camp hospital, Durand said.

The detention camp at the U.S. naval base in Cuba holds about 460 prisoners in five separate compounds. Durand said guards were searching all of the cells for contraband.

The United States has faced criticism from human rights groups and some of its allies for holding prisoners at Guantanamo indefinitely. Some have been there since the camp opened in January 2002.