Several people Monday morning protested outside of the office of an energy company in Rohnert Park, hired by PG&E to install new utility meters in Sonoma County.

Late Monday morning Rohnert Park police were called because six protesters were blocking the entrance to the business, said Lt. Jeff Taylor.

"We responded and told them to not block the driveway. They cooperated and left..." Taylor wrote in an email.

The protesters were members of the EMF Safety Network, a Sebastopol-based group protesting the new meters.

They gathered outside an office of Wellington Energy Inc. at about 7 a.m. on State Farm Drive.

"Our message to them is this has to stop. We're protecting our health and our privacy rights," said Deborah Tavares of Sebastopol.

Tavares early Monday said about a dozen people were involved in the protest.

The group fears the radio frequencies used to transmit data from SmartMeters, coupled with those coming from a myriad of other electronic devices in use in everyday life, can lead to a range of health problems.

No definitive links between radio frequencies and ill health have been found by the World Health Organization, American Cancer Society and other major health organizations. The group calls those studies and PG&E efforts to protect their customers inadequate, Tavares said.

Pacific Gas and Electric Co. is converting to SmartMeters around the state. The meters have a "smart grid" allowing consumers to access their energy use data in real time online and also gives the company immediate use and billing information.

There are about 400,000 meters to be changed out in Sonoma County. More than half of those already have been swapped.

PG&E contracted with Wellington for the job.

The protest kept the contractors from heading out to installation jobs for several hours, a PG&E spokesman said.

"The trucks were unable to get out until noon," PG&E's Paul Moreno said.

The utility company had upgraded about 60 percent of the electric and gas meters in the county's nine largest cities as of Nov. 12, according to numbers provided by Moreno.