"This is an animal strain of the H1N1 virus and it has pandemic potential because it is infecting people," Dr. Margaret Chan said Saturday speaking to reporters by phone.
In Mexico, 68 people have died from swine flu, according to a statement from the U.S. Embassy in Mexico.
Eight people were confirmed to have swine flu in the United States; six in California and two in Texas, according to the U.S. Centers for Disease Control and Prevention.
All eight have recovered, according to CDC's acting Director Richard Besser.
CDC has tested 14 samples of the virus from Mexico and found seven were identical to the virus found in the U.S. cases, Besser said.
"This situation has been developing quickly," he said. "This is something we are worried about."
Asked whether the committee would address raising the agency's alert concerning the virus to 6, a pandemic alert and the highest level on WHO's scale, Chan said, "Yes, indeed."
The alert stands at 3, meaning "No or very limited human-to-human transmission."
Chan said Saturday that WHO does not have indications of similar outbreaks elsewhere.
However, she said, "The situation is evolving quickly. A new disease is by definition poorly understood."
White House spokesman Reid Cherlin said Saturday that the White House was taking the situation "seriously and monitoring for any developments."
Health officials in Texas announced Saturday the temporary closure of Byron Steel High School in Cibolo, Texas, where swine flu was confirmed in two students earlier this month.
"The purpose is to reduce the risk to students, staff and the community," said Dr. Sandra Guerra, a public health official in Guadalupe County, Texas.
Mexico City has closed all of its schools and universities until further notice because of the virus, and on Saturday, the country's National Health Council said all soccer games would be played Saturday without public audiences.
