(AP)—Union officials say hundreds of nurses in the San Francisco Bay area are braving rain showers to walk picket lines after going on strike Tuesday.

A spokesman for the California Nurses Association says registered nurses at eight hospitals operated by Sutter Health walked off the job around 7 a.m. Tuesday in what will be a two-day strike. Nurses at two San Jose hospitals operated by Hospital Corporation of America went on strike for one day.

The hospitals have hired replacements on five-day contracts to take the place of the striking nurses. Because of the contracts, hospital officials say the striking nurses won't be allowed to return to work until Sunday.

The strike is the seventh by CNA since September 2011. It comes as union leaders and the hospital officials remain at odds over health benefits, and other issues.