Fears of a "cluster" are circulating in the town of Cameron, Mo. as more than a dozen residents have been diagnosed with brain tumors in the past seven months, KMBC.com is reporting.

Pharmacist Steve Erickson was among the first in the town of 6,500 to become concerned over the flurry of brain tumor cases. Erickson told KMBC.com that he knows most of the families in town and immediately realized something was wrong.

Most of the tumors diagnosed in Cameron are large, but benign. Because doctors are only required to report cancerous tumors to the state Health Department, no agency is officially collecting data on the occurrence.

The one thing residents have in common is drinking water. A single reservoir is the source of the town's water supply. The Centers for Disease Control and Prevention said it will look at any possible runoff near the reservoir and any possibility of contamination from a nearby hog farm, the Web site reports.

The Department of Natural Resources has sent a crew out to collect air, water and soil samples.

Click here for more on this story from KMBC.com.