The first fatality from swine flu in the United States, a 23-month-old child, was identified as a Mexican who was in Houston for medical treatment, a health official said on Wednesday.

"The family had traveled to South Texas. The child became ill and they took the child to Houston for medical care," Houston health department spokeswoman Kathy Barton told the CNN by telephone.

Barton said she did not know from which part of Mexico the child came from.

Earlier, Richard Besser, acting director of the Centers for Disease Control and Prevention, told the CNN's "American Morning" program that "a child has died from the H1N1 virus."

"As a parent and a pediatrician, my heart goes out to the family. As I've been saying for the past few days flu is a very serious infection, and each virus is unique so it is hard to know what we're going to be seeing," Besser said. "But given what we've seen in Mexico we have expected that we would see more severe infections and that we would see deaths."

"Flu is a very serious disease, and we're treating this outbreak very seriously," Besser also said on CBS' Early Show. "We're taking aggressive action to try and control this."

"It's very important that people take their concern and channel it into action," Besser said, urging Americans again to wash their hands often and cover their mouths when coughing or sneezing.

"I don't think it (the reported death in Texas) indicates any change in the strain," he added. "We see with any flu virus as a spectrum of disease symptoms."

The child is the first person to die of swine flu outside of Mexico where the virus has caused more than 159 deaths and roughly 2,500 illnesses.

U.S. officials have confirmed 64 cases of swine flu. Most of them have been relatively mild, with only a handful of sufferers requiring hospitalization.

In remarks at the White House before leaving on a one-day trip to Missouri, President Barack Obama said the U.S. government is "closely and continuously monitoring the emergent cases of this virus throughout the United States."

"This is obviously a serious situation. Serious enough to take the utmost precautions," Obama said.

The president also said that the closure of schools in some instances may be necessary, especially in cases of confirmed infections.

It is the recommendation of public health officials "that schools with confirmed cases ... should consider closing if the situation becomes more serious," Obama said.

So far, the World Health Organization said at least 112 human swine flu cases have been confirmed worldwide.