District Police Chief Supt Peter Umbuas said the boat had just left the Semporna general jetty and was heading to the school when it started to leak in the Tobo-Tobo waters about 7am.
He said the boat did not capsize or sink but water started leaking into it.
"The skipper's quick decision to speed towards SK Larapan jetty prevented the situation from getting worse," he said, adding that they arrived at the school's jetty safely about 7.35am.
He said all the passengers escaped danger when the boat reached the shallow waters near SK Larapan, located close to SK Sumandi, which is about nine kilometres from the mainland.
"There are no further details as the victims have yet to lodge a police report," he added.
Meanwhile, Semporna District Officer Dr Chacho Bullah said he had requested for a report on the incident from the parties concerned.
Several incidents involving boat capsize at sea have been reported in the State in the past two months.
Among them involved nine anglers and five crew who were plucked to safety when the two-storey catamaran they were on encountered problems between Pulau Tiga and Pulau Sulug on Feb 13.
On Feb 7, a boat carrying 15 people including its skipper capsized off Tawau waters.
Fourteen of the 15 victims were found but only four survived.
A catamaran carrying 28 China tourists and three crew also capsized near Pulau Mengalum off Kota Kinabalu on Jan 28, with five of them remaining missing as at press time. - Lagatah Toyos