The investigation into the cause of a housefire in Fairfield has yielded some shocking new developments.

Fairfield police have arrested and charged 36-year-old Mikaelle Rosw with third-degree arson after witnesses reported she intentionally started the fire in the back of her Castle Avenue duplex.

"Wow, that's crazy that someone would set fire to their own house," neighbor Rosemary Roldan says. "That's really sad."

Firefighters responded to the corner of Castle and Longfellow avenues around 3 p.m. Thursday, where flames were coming from the back of the multi-family home.

"We live right down the road," neighbor Liam Mason says. "We were walking the dog, and the next thing we know, there were a bunch of sirens."

Firefighters knocked down the blaze, and no injuries were reported. During the investigation, Fairfield police say witnesses reported seeing one of the homeowners intentionally set fire to the outside of the house before taking off in a car.

Authorities say officers quickly located the car and eventually arrested Rosw.

She was held on a $500,000 bond.

"I've just told people that yesterday, there was a fire on my street," neighbor Alex Weber says. "Then with the follow-up today... It makes people go 'wait, what?' It's pretty wild."

Neighbors are speculating about the circumstances surrounding the incident.

"Maybe she was having some issues with her life," Roldan says. "I don't know, but that's really sad."

"I'm sure there's a lot of things going around out there about motive and why," Weber says, "and what was the owner allegedly after."

The multi-family home has been deemed uninhabitable by fire officials.