Toronto transit officials are saying that it was a just coincidence that three subway passengers fell ill at Dupont station within a short timeframe on Tuesday.

The three separate incidents caused a half-hour subway delay during the morning rush.

Paramedics were first called to Dupont station just after 8 a.m. after a passenger who felt ill activated the alarm system.

A pregnant woman, who was travelling on the same train, also needed help after falling and striking her head, transit commission spokesman Danny Nicholson told The Canadian Press.

About a half-hour later, a third person fainted after a mysterious odour was emitted from outside the building, Nicholson told CP.

Fire officials have yet to determine the source of the odour, but tests for carbon monoxide and other noxious elements were negative.

Five other calls for assistance were also made during the Tuesday morning commute but Nichoson told CP these call are "not unusual for a hot morning rush hour."

With files from The Canadian Press