The 9:30 a.m. Mass at St. Cyril of Jerusalem Church along the 1400 block of Almshouse Road had just began when two teenage parishioners fainted.
"After that a third teenager came back and said she wasn't feeling good and we just continued on with our service and while the [medics] came in to take care of these three people," Monsignor Robert Powell said.
But when the medics began feeling ill, firefighters were called in.
Bucks County Hazmat crews responded and immediately evacuated the church.
Then the emergency responders came to be overcome by the fumes that were making the parishioners sick.
"As more and more were sickened, more and more resources were called, and became clear it was a hazmat incident and not something else," Lt. Mark Goldberg of the Warwick Township Police said
As many as eighteen people were sickened inside the church. Among the victims were six parishioners, five firefighters, two police officers and five EMS officials.
Police officials say the victims were hospitalized for a time but later released and are said to be doing fine.
Hazmat crews determined the air quality inside the church to be clean. They are still searching for what was causing people to be lightheaded, dizzy, and nauseous.
A heating company was brought in and it could not determine a cause either.
"Our heating people came in and went through the system...and they say they didn't see any source from the units," Powell said.
Warm temperatures allowed 10:00 a.m. and Noon Masses to be held outside.
Monsignor Powell says the fire department deemed the building safe and Mass will go on as planned on Monday. But what exactly caused Sunday's scare remains a mystery.
"It's best for us to always be cautious and that's basically what we were," Monsignor Powell said.