WICHITA, Kan. -

Investigators are still trying to determine how all the fires started in the Wichita area Thursday.

But, authorities say a passing semi is likely to blame for some of the fires.

The Andover Fire Chief tells us his department responded with about two dozen firefighters.

He estimates the fire there burned about 35 acres.

In Wichita, the fire department had to call in off-duty firefighters to assist.

Two battalions of firefighters from one shift were called into reserve status to make sure the city was still covered.

The city also stopped responding to minor medical calls.

"We did alter our response guidelines, a lot of the basic medical calls, we weren't going out to," said Captain Stuart Bevis.

No one was hurt in the fires, and no major damage has been reported.

"This was an extremely taxing event for the fire department," Bevis said. "We had a lot of resources expended trying to track all of these down and get them under control."