Krissi and Shane McCollow were 5 miles away from the church in Nashua, Ia., where they would exchange their vows, start a new chapter as husband and wife and celebrate with loved ones.

Then a weird aroma and thick smoke began billowing inside their party bus.

"I was worried that it might stop and we may not get to the church," Krissi, 26, told the Register on Monday afternoon during the newlyweds' "mini honeymoon" at Mystic Lake Casino in Prior Lake, Minn. "I just knew something wasn't right because of the smell and smoke."

The bus made it to the church on Saturday, everyone safely exited, the last cooler of alcohol was retrieved and moments later ...

"It literally exploded," Shane, 29, said of the bus erupting in flames. "It sounded like a gunshot."

Krissi said when they first entered the bus upon leaving Cedar Falls for Nashua, about a 35-minute drive, it was "super hot" inside. They asked the driver to turn on the air conditioning, but then the bus became frigid. The driver flipped the switch once more.

"That's when we started to smell a weird smell," Krissi said. "It started to get smoky on the bus," which progressively worsened.

Nick Sorbe, owner and manager of Dolly's Party Bus service, said Monday the fire was caused by a leak from one of the bus' brake chambers, which created the smoke. As it worsened, the bus became overheated and a small fire sparked.

A new bus was immediately sent to Nashua — with Dolly's waiving all fees, Krissi and Shane said — and transported the group to the reception following the ceremony. The couple credits the "fantastic work" provided by the busing service, as well as the local fire department and church staff, given the circumstances on their special day.

Dolly's has experienced this situation at least one other time. In March 2013, eastern Iowa TV station KWWL reported a 50-passenger Dolly's bus engulfed in flames on Interstate 380, with its air conditioning unit suspected as the cause of the fire. The driver was the only person on board, and no injuries were reported.

Krissi, Shane and their bridal party made the most of Saturday's situation simply by laughing about it, which the couple said is fitting for them. So what better way to capture and remember the moment than photographs?

McKaila Hanna was the photographer at the ceremony and reception. She and her husband — who was her second shooter for the day — said they sat in the same spot where the fire originated. She added that two of the bus' tires had popped in the process.

Hanna said her goal during each assignment is to "tell a story from beginning to end." And when she saw the flames, Hanna knew Krissi and Shane would need memories of this documented in their wedding album.

She took a photo of just the newlyweds, a few of all of the groomsmen "joking around" as well as the entire group standing in front of the fiery bus.

Hanna noted how relaxed and collected Krissi was throughout the ordeal, saying she checked to make sure everyone was OK.

"I can't believe as a bride she was that calm," Hanna said.

Hanna later shared some of her photos on her Facebook page early Sunday morning, writing: "Interesting unplanned entrance to a wedding ceremony today. Little Brown Church in the Vale survived and the Nashua Fire Department saved the day!"