Emergency workers have responded to five fires since Thursday.
Police arrested three teen girls in connection with a Thursday fire on the 2200 block of West Main.
On Saturday morning police rushed to trailer fires on the N. 17th and East Main, and a dumpster on fire near N 7th and Tamarack.
And early Sunday morning a fire destroyed a home under construction at 3700 Pipestone Drive.
"I think it weighs on everybody in the neighborhood, when somebody would just blatantly start somebody's house on fire with them sleeping inside of it, that's a dangerous person," said neighbor Matt Rivnie.
Just after midnight on Sunday, Rivnie let his dogs into the backyard. Immediately he noticed a home, still under construction, on fire.
He says the fire took over the entire house in a matter of minutes.
"The fire just spread fast, fast, it went from just a small fire inside the house to the whole house being engulfed within minutes," Rivnie said.
The Pipestone fire was one of five fires that took place between Thursday night and Sunday morning.
Law enforcement officials are calling them all suspicious.
"And we firmly believe that at least one or more of these fires are deliberately caused. It's too early to say that with certainty, until we do what we have to do," said Deputy Police Chief Rich McLane.
McLane says one or two fires over a weekend could be anything, but with this many, it's a different story.
"When you have five on the heels of some pretty major fires with the Heritage Christian School amongst others, we start looking at that with a little sharper eye and we are considering and certainly not ruling out that these are somehow connected," he said.
The house on Pipestone was still under construction when it was destroyed by fire. That means it wasn't set up with electricity or gas, which can sometimes spark a blaze. That's just one of several reasons why law enforcement officials are calling the cause of the fire suspicious.
"There's nothing in our processing that says these were totally by accident or totally explainable yet," McLane said.
As law enforcement continues the investigation, Rivnie says he worries about whoever may be starting them, and their disregard for people's properties and lives.
"I mean people work a lot of years to build a house and to buy a home. And for somebody to just throw a match to it is just beyond me," he said.
"We just need to identify who's doing it and we need to put a stop to it," McLane said.
Police say if you have any information that could lead to an arrest or see anything suspicious call them at 582-2000 or Crimestoppers at 586-1131.