Sheikh Rashid bin Mohammed bin Rashid Al Maktoum, the son of the ruler of Dubai, died of a heart attack on Saturday, the state media reported. He was 33.
Sheikh Rashid was the son of Sheikh Mohammed bin Rashid Al Maktoum, the vice-president and the prime minister of United Arab Emirates (UAE), and the ruler of Dubai.
UAE President Sheikh Khalifa bin Zayed Al Nahyan declared a three-day official mourning following Sheikh Rashid's demise, WAM news agency reported.
Sheikh Rashid was a horse racing enthusiast.
In a message, Sheikh Saud bin Rashid Al Mu'alla, the ruler of Umm al-Quwain (UAQ), one of the seven emirates of the UAE, mourned Sheikh Rashid's death.
In his condolence to Dubai ruler Sheikh Mohammed, the UAQ ruler "prayed to almighty Allah to rest departed soul in paradise and grant solace and patience to the family".
Abu Dhabi's Crown Prince and Deputy Supreme Commander of the UAE Armed Forces Sheikh Mohamed bin Zayed Al Nahyan also conveyed his heartfelt condolences to Sheikh Mohammed and the Al Maktoum family.
Fujairah ruler Sheikh Hamad bin Mohammed Al Sharqi also mourned Sheikh Rashid's death and in his condolences to Sheikh Mohammed, he prayed to Allah "to rest the departed soul in paradise and grant patience and solace to the bereaved family".
Sharjah's ruler Dr. Sheikh Sultan bin Mohammed Al Qasimi mourned the death of Sheikh Rashid and prayed to almighty Allah "to rest the departed soul in paradise and grant patience and solace to bereaved family".
Ajman ruler Sheikh Humaid bin Rashid Al Nuaimi prayed to almighty Allah to rest the departed soul in paradise.