Arson investigators are now hard at work in Seminole County as they try to solve six fires.

Each one was set this week, and investigators with the state fire marshal's office say all of them are suspicious.

Four of those fires were set this morning in Sanford.

One of the buildings burned was a historic school house, built in the the late 1800s, and irreplaceable historical memorabilia may be forever lost.

Investigators from the State Fire Marshal’s Office are trying to figure out a motive and possible suspects.

But they do know one thing for certain, the fire that destroyed the historic Little Red Schoolhouse overnight Wednesday, and five other fires in the area this week were all intentionally set.

It all started Monday when firefighters battled fires at two vacant homes in Sanford.

And just blocks away this morning, investigators say someone set fire to another vacant home, and the historic Little Red Schoolhouse on 6th Street and Palmetto Avenue, built in the late 1800s.

The fire destroyed the building, and centuries of history, in just a matter of minutes.

“Somebody just took a piece of Sanford and stomped all over it. And you can’t just go back and replace anything, the building, the school house, what’s in it. It’s just gone,” said Sanford resident Kerrie Swift.

Fire investigators say all four of Thursday morning’s fires, which were just blocks apart, were the work of at least one arsonist.

They’re now trying to figure out if two other fires off North Ronald Reagan Boulevard just outside of Sanford, were intentionally set and possibly connected to Thursday's fires.

Investigators are now asking for help from the public.

“We really rely on the public, even if they see something suspicious without a fire happening,” said Lt. Paul Paterson, State Fire Marshal's Office.

And all of the fires have left people on edge.

“I have a lot of property here, and I’m very concerned cause I have one that’s empty. And God forbid they do this to mine,” said nearby resident Theresa Spano.

And the city wasted no time in tearing what was left of the historic school house down. The city was trying to sell it, in order to restore the building.

But all that’s left now, is a huge stack of burned rubble.