They gained "inappropriate access" to the mayor's medical records at Humber River Hospital, the hospital's communications director Gerard Power confirmed in a written statement.
The hospital's president and CEO, Rueben Devlin informed Ford of the breach of privacy Wednesday, said Power, following an investigation that revealed the security lapse.
Power did not say whether the individuals were staff members, but said "appropriate disciplinary action was being taken" against them.
Last week, Mount Sinai Hospital announced a similar breach of privacy. Two staff members not involved in Ford's care were disciplined after accessing Ford's medical records.
Ford, 45, was diagnosed with liposarcoma, a rare type of cancer, in September after a tumour was discovered in his abdomen.
He was initially running for re-election in Toronto's mayoral race, but withdrew his name from contention shortly after falling ill. Ford cast a ballot during advance voting for his elder brother, Doug Ford, who entered the race for mayor in his place just before the deadline.
Advance voting closed Sunday. The city released figures from the six-day period that showed that more than 160,000 ballots were cast. In 2010, only 77,391 advance poll ballots were cast.
Rob Ford is now running as a candidate for Ward 2 councillor, where he served for a decade before he was elected as mayor in 2010.
Election day is Oct. 27.