Sayyiduna Sinan bin Arafah (may Allah be pleased with him), whose companionship (of the Prophet) is established, narrates from the Prophet (peace and blessings be upon him) concerning a man who dies among women, and a woman who dies among men, when neither of them has a mahram present, that he (peace and blessings be upon him) said: "Tayammum should be performed for them both, and they should not be washed (given ghusl)."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6467