The incident happened during the 9:00 a.m. mass Sunday inside St. Cyril of Jerusalem Roman Catholic Church.
Investigators still have no idea what those fumes were or where they came from.
What has first responders most confounded is the fact that each of the original three parishioners who fell ill were all in different parts of the building at the time.
"The concentration of the gas in what we thought was a problem area was not located in one area of the church. The subjects in question were not seated near each other. It's very unusual," said Raymond Hackman of Bucks County HAZMAT.
The scene grew increasingly chaotic as the building was evacuated after a few more parishioners reported feeling faint.
Then, responding paramedics and firefighters began experiencing dizziness and nausea as well.
Air quality tests performed at the scene came up negative for carbon monoxide, natural gas, and other noxious fumes and no problems were detected with the furnace.
Police say they do not suspect foul play.
"We have not found any indication of any kind of foul play. There have been no suspicious packages, no threats, no evidence of anything like that at all," said Lt. Mark Goldberg of the Warwick Township Police.
Several air quality monitors are now in place in locations throughout the church and St. Cyril has been given the OK the reopen for all of its weekday activities.
However, church officials say they will stay on top of this matter until the mystery is resolved.
"We want to deal with anything that needs to be dealt with," said Msgr. Robert Powell. "It could be one of any number of things."
Several of those sickened were taken to nearby hospitals, treated and released, without knowing what made them sick.