According to press reports, Marin County health officials are investigating a potential E. coli outbreak after the bacterial infection was detected in three children and is suspected in an adult.

Three people sickened live in Tiburon; a fourth lives in Inverness. No definitive source for the bacteria has been identified, but health officials believe the residents were exposed to the bacteria between Sept. 11 and Sept. 15. There have been no new documented cases since the initial outbreak.

Dr. Matthew Willis, Marin County public health officer, said E. coli infections are most serious in children, elderly people and those with weak immune systems.

“Three of the four cases are children and two of them have been hospitalized, but are in stable condition,” Willis said.

He said Marin public health authorities are working with the California Department of Public Health to gather information from clinicians and patients to determine whether the cases are linked to each other or possibly to out-of-state cases.