California officials assured the public on Monday that schools in the state remain saft despite a declared national health emergency.

Parents should not be worried about sending their children to classes, State Superintendent of Schools Jack O'Connell said.

"Our schools in California are safe," O'Connell said. "We want to make sure our parents and professional educators do everything they can to keep our schools safe."

He said local school administrators can download a free "Keep Our Schools Healthy" toolkit that includes sample letters to send home to parents and posters to place on campuses to remind children about proper hygiene. The toolkits come in multiple languages, O' Connell said.

To keep the outbreak in perspective, only a few children out of a state enrollment of 6.3 million students have been infected, he said.

A total of seven swine flu cases have been reported so far in California, indicating the potential for a swine flu pandemic, health officials warned earlier.

Four cases were reported in San Diego County and three in Imperial County, both in Southern California. The latest victim, a35-year-old Imperial County woman diagnosed April 4, has since fully recovered, according to the California Public Health Department.

California Governor Arnold Schwarzenegger has opened an emergency operations center, where public health officials are monitoring the progress of the virus and coordinating their response with federal health officials.

There have been about 20 confirmed cases of swine flu in the United States so far.

Swine flu is usually transmitted to humans by pigs, but public health officials are concerned about the possibility of a pandemic because the new strain appears to be spreading from human to human.

"That sounds more severe than really it is," Homeland Security Secretary Janet Napolitano said when announcing the nationwide health emergency on Sunday at a White House news briefing. "This is standard operating procedure and allows us to free up federal, state, and local agencies and their resources for prevention and mitigation."

To avoid the disease, experts recommend washing hands frequently. If you are sick, avoid contact with others. So far, an effective vaccine has not been developed.

Symptoms include a fever of 100 degrees or more, vomiting, coughing, a sore throat and diarrhea.

No swine-flu-related deaths have been reported in the United States.