Officials were trying to determine the extent of the outbreak, CDC spokesman Tom Skinner said Sunday.

CNN: STORY HIGHLIGHTS

"However this virus may already be in other places in the United States, " CDC spokesman Tom Skinner told CNN.

CNN: Regular flu season precautions advised in current outbreak

"We've only got the two cases to go on and both kids recovered on their own, so that's certainly good news, " says Tom Skinner, a CDC spokesman.

CNN: CDC: Swine flu seen in 2 California children

Tom Skinner, a CDC spokesman, said the agency has sent H1N1 strains to roughly seven labs around the world to use in the first steps of vaccine development.

CNN: 'We are not out of the woods' with new flu, CDC warns