CHICAGO (CBS) — When severe weather hit north-central Illinois last week, there was an army of volunteers out gathering information, and funneling it to the National Weather Service to provide a more accurate picture of what was going on.

Among those volunteers were amateur radio operators.

Tom Ciciora has been involved in amateur radio, or ham radio, for more than 40 years. He said, when thunderstorm or tornado warnings are issued by the National Weather Service, amateur radio enthusiasts will head toward areas where it might be worst, using smartphone app radar as a guide.

“When this thing initiated, there were folks in the correct place, making reports back to the weather service, and all along its path,” he said.

He called what happened Thursday evening, when a deadly tornado hit near Rockford, “quite a group effort.”

Ciciora said enough warning went out as a result, that – even though two people were killed – most people were able to get to someplace safe, and minimize any injuries.

Two women were killed and 20 people were injured, after an EF4 tornado hit the towns of Fairdale and Rochelle, just south of Rockford.

Bill Nelson, Observation Program Leader for the National Weather Service office in Romeoville, said, when severe weather hits, ham operators are “our eyes on the ground, as they can reach out to other ham members, and tell us what’s actually going on out in the real world.”

Nelson said, when severe weather is in the area, at least one amateur radio operator sets up in the NWS operations room, right next to the coordinator, and communicates with ham operators in the field.

“It completes the picture of what we do see on radar and gives us ground truth,” Nelson said.

Ciciora was quick to point out it’s not just ham operators out there providing information, but other trained spotters and storm chasers, as well.