She said Willis is “resting comfortably” but could not provide details about his condition because doctors were still running tests.
Willis was initially transported by ambulance from work to the emergency room about 9:20 a.m., City Administrator Fred Russell said.
At the hospital, Willis had his wife, sons and a couple of firefighters by his side.
The incident appears unrelated to any department physical testing or activities, Russell said.
With Willis out, Mike Rogers, the deputy chief over technical services, is in charge, Russell said.
Rogers said administrators at the office made the decision to send Willis to the emergency room, although he would not describe what kind of complications Willis was having.
“It was a medical condition we thought he probably needed to be looked at,” Rogers said.