A 19-year-old Emirati police cadet died while taking part in a morning training session at the Sharjah Federal Police School.
The man, identified as AAS, had finished morning prayers and was taking part in regular exercises on Monday when he suffered a suspected heart attack and collapsed, a police spokesman said.
"Students, together with the academy doctor, tried to give him first aid and called an ambulance to take him to Al Qassimi hospital.
"Police are investigating."
Hospital staff said AAS was dead when he arrived at the emergency department at around 7am.
"He was pulseless when he got here," said Dr Arif Al Noryani, the hospital's CEO. "Our team tried to resuscitate him for about 35 minutes but all was in vain and they declared him dead."
AAS was buried by his family in Fujairah on Monday.