The incident was believed to have occurred at 5.50pm.
Semporna Tourism Association chairman Jamilah Ang Kher Lern, when contacted, confirmed the incident.
Meanwhile, Semporna district police chief Sabarudin Rahmat said details of the incident would be released later.
In Kota Kinabalu, state Tourism, Culture and Environment Minister Christina Liew said the two tourists killed in the incident were from China.
“We have informed the consul-general of China in Kota Kinabalu and the Sabah chief minister about this tragic event.
“Our Sabah Tourism Board officers are on standby to monitor the situation,” she said in a statement here.
She added that the incident occurred outside the Tun Sakaran Marine Parks.
Liew also urged the Eastern Sabah Security Command (Esscom), marine police and Fisheries Department to take a serious stand against fish bombing.