THOMASBORO, Ill. (WCIA) — When three tornadoes touched down in Champaign County on Monday, the region’s tornado sirens activated to warn people of the dangerous weather.

But not in Thomasboro.

Despite being in an area where a tornado warning had been declared, the sirens there stayed silent. The people who live there wanted to know why.

Thomasboro Mayor Tyler Evans said people were monitoring the storm, but saw no rotations and decided not to turn them on. The town does not have automatic sirens. He said it is too expensive for the town to upgrade their manually activated sirens to automatic.

So what is the difference between automatic and manual sirens?

Pete Mantell with Sidney Emergency Services and Disaster Agency said the National Weather Service will first send out a warning.

“A polygon will be drawn by the National Weather Service and then immediately, all the sirens that are within that polygon automatically snap on,” Mantell said.

A polygon is an area drawn on a map of where a storm is and where it is going. Sirens will go on automatically go on if they are in the polygon. But if an area doesn’t have automatic sirens, someone has to manually turn them on.

“We have three sirens here in Sidney, and originally, the way our system used to work is, literally, you press a button manually and that would set off the sirens,” Mantell said.

Mantell said one of the sirens in town was installed in the late 60s and it’s probably been since the late 80s that someone had to manually turn it on. Now anyone can turn them on and do a test with the press of a button from a phone or app.

But there still are some towns in the area that require a person to manually activate their sirens, either by hand or by sending a radio signal.

John Dwyer, Champaign County EMA Coordinator, mentioned St. Joseph, Ogden, Homer and Thomasboro as some of these towns.

So what happens if the person in charge isn’t around or can’t get to the siren? What do people do then?

“Hopefully they have a backup plan,” Mantell responded.

Dwyer said it’s also up to people to stay informed. He said that counties aren’t legally mandated to have or turn on outdoor sirens.

“Cell phones, TV, a NOAA weather radio,” Dwyer said. “And besides, these are for outdoor warnings. What if you are already taking shelter indoors and you can’t hear them?”

Dwyer said manual systems aren’t necessarily a bad thing. Having the capability to set sirens off himself actually helped during Monday’s tornadoes. Dwyer said he heard a tornado touched down before an NWS tornado warning was even issued, so he set the sirens off early.