McALLEN, Texas -- Texas state health officials confirmed Tuesday the first death of a United States resident with swine flu.

The patient, a 33-year-old schoolteacher from Harlingen who recently gave birth, died early Tuesday after contracting swine flu, said Leonel Lopez, Cameron County epidemiologist.

Harlingen is a city of about 63,000 near the U.S.-Mexico border.

State health department spokeswoman Carrie Williams said the woman had "chronic underlying health conditions" but wouldn't give any more details.

The exact cause of death wasn't immediately known.

She was first seen by a physician April 14 and was hospitalized on the 19th. The woman delivered a healthy baby while hospitalized and stayed in the hospital until her death, said Lopez, who declined to give further details about the baby.

Dr. Joseph McCormick, regional dean of the University of Texas School of Public Health's Brownsville campus, said the woman was extremely ill when she was hospitalized.

Mercedes Independent School District, where the woman taught, announced it would close its schools starting Wednesday and reopen May 11.

Based on the time the patient was admitted to the hospital and began to show symptoms of swine flu, anyone who had contracted the disease from her would have shown symptoms by now, McCormick said. Lopez also said students and employees of the school district where she worked shouldn't worry if they are currently healthy.

McCormick said he was working with the county to track "several hundred" possible cases that are being tested to determine whether they are swine flu.

The woman's death Tuesday is the second death in the United States. A Mexico City boy who also had underlying health problems and was visiting relatives in Brownsville, near Harlingen, showed symptoms of swine flu and died last week at a Houston children's hospital.

State health officials said Texas has 61 cases of swine flu.