TEQUESTA, Fla. — A man who may have been on hallucinogenic drugs fatally stabbed a couple at their home and wounded a would-be rescuer before deputies found him biting the dead man’s face, authorities said Tuesday.

Martin County Sheriff William Snyder told reporters that a man in his 20s may have been on drugs when he attacked the couple at their Tequesta home late Monday and the neighbor who tried to stop him. Authorities were still trying to confirm the suspect’s identity.

Snyder said deputies found the man on top of the dead husband and it took several attempts and a dog to pull him off. The names of the victims haven’t been released. Snyder said the neighbor is hospitalized with ‘‘substantial trauma.’’