The odor of natural gas in Davenport's western half Monday morning led to evacuations at several schools and part of Genesis Medical Center. 

Officials haven't determined the source of the foul smell that caused concern at eight schools. About 1,700 students -- from North High School, Harrison Elementary School and the Kimberly Center -- were evacuated for about 20 minutes, between 10 and 11 a.m., school district spokeswoman Dawn Saul said.

Five other schools -- Smart Intermediate, Monroe Elementary, Adams Elementary, Williams Intermediate, and Children’s Village West -- also were affected, but building staff determined the smell was worse outside and students stayed indoors, she said. 

MidAmerican Energy was notified and investigated.

"It was not coming from our system; we had no leaks," MidAmerican Energy spokesman Tim Grabinski said Monday afternoon. "We can't tell where it was coming from."

Similar to an incident a month ago, Monday's "rotten egg smell" extended farther north, Ms. Saul said. No students or staff got sick from it, she said. 

Some at Genesis Medical Center on West Central Park Avenue were not so lucky.

"Several employees self-evacuated the building because they were nauseous. Several employees felt sick and went outside or went home," Genesis Health System spokesman Craig Cooper said. "There was not an official evacuation."

An odorant added into the odorless gas before it is inserted into the distribution system gives off a foul smell, reminiscent of rotten eggs or sulfur, Mr. Cooper said. At about 10 a.m. Monday, there was a noticeable odor of the additive at Pavilion 1 of Genesis, he said. 

"It is always disconcerting to notice that odor," he said.

Four patients did not receive scheduled radiation treatment in the Genesis Cancer Care Institute, Mr. Cooper said, adding that staff was working on getting them back later Monday. Several employees left and returned later when the odor had dissipated.

Infusion patients all received scheduled infusions, Mr. Cooper said. The Davenport Fire Department ran monitors in Pavilion 1, but did not find unusual levels of natural gas, he said. Cancer Center operations were back to normal Monday afternoon.