"Fire, fire, fire and it's extremely loud," recalled Karlsen.
The women say they had a contract with Vector Security to monitor their home alarm system and knew from their experience during a prior alarm - which turned out to be false - that they'd get a call from Vector or see the fire trucks show up any minute. So, instead of running away, or wasting time calling 911, they tried to fight the fire.
"I grabbed the water hose, she had a water hose, thinking we could stall it," explained Yost.
"So you're thinking, 'OK any minute now we'll see firemen and fire trucks here to help us with this fire,' and it never happened," said Karlsen.
Never happened, even though that's what they say they paid for when they bought their Vector security system. They expected it to be constantly monitored and for Vector to dispatch fire and emergency crews if an alarm went off.
"The goal is to get here fast. If you wait 15-20 minutes, you've lost a lot more than if they had been here in 5," said Karlsen.
And as the minutes passed, so did their chances of controlling the blaze.
"Eventually, we went up to the neighbor's house and we called 911," said Karlsen.
After that call, fire departments from Chapel Hill and Hillsborough showed up, but not before $250,000 worth of damage had been done.
So what did Vector have to say about the alert the women say it missed? They claim they heard nothing for days.
"They did not even contact us and the house was not being monitored for three days. I had to call them to say our house was burnt," said Yost.
But that call just led to more frustration.
"We asked them to come out here and take a look and see what happened. Did your system fail? Do you need to change something? They never came out," said Karlsen.
They eventually got a supervisor on the line.
"He said 'Since your house is completely destroyed, we can't investigate anything.' I said, 'Your source is wrong, our house isn't completely destroyed. The Vector pad and everything was untouched. It's on the other side of the house,' I said 'I would like you all to come,'" said Yost.
And when the women say Vector wouldn't, they cancelled their service and told Vector they held them responsible for their loss. But Vector's insurance company pointed out that, in their contracts, there's a $1,000 liability limit if the system fails to operate properly.
The women reluctantly took the thousand dollar settlement so they could put it all behind them.
"Our energy is focused on rebuilding our house and we don't want anyone else to go through this," said Yost.
But while they're rebuilding, they're also speaking out and warning others
"I don't want anyone to go through and may not be as fortunate as we have been, not with the peace of mind that you're being monitored when you're not," said Yost.
I did get in touch with Vector and they said they'd look into this case, but they never got back to me. The best advice for anyone with a home security system: test it often and confirm each time that you're being monitored.