BUENOS AIRES, Argentina - Argentines worried they may have swine flu have overwhelmed some emergency medical services at the onset of the South American winter flu season, health officials said Wednesday.

The Health Ministry said Argentina's confirmed caseload has grown to 281, with an additional 1,032 possible cases being studied in labs. More than two-thirds of those sickened were young people, and 29 schools in Buenos Aires and the surrounding area have been closed for two weeks after children tested positive.

Sergio Alejandre, hospitals director for Buenos Aires province, said Wednesday that public hospitals are beefing up because with the arrival of the Southern Hemisphere winter, "consultations begin to increase ... for respiratory problems, adult flu and bronchitis in children."

Though the number of confirmed cases is less than one-sixth of neighbouring Chile's caseload, so many Argentines are seeking treatment that emergency services have "collapsed" in and around the capital, Carlos Chiarelli of the Chamber of Medical Emergencies said at a news conference. "A single company fielded 10,000 calls yesterday (Tuesday)."

Federico Diaz Mathe, director of national health organization Cimara, said fears have led to an "excessive demand," so emergency crews do not have enough ambulances, doctors or nurses for those seeking help.

"If this gets worse, medical services will have to select their patients. If they have certain symptoms, keep an eye on them; if other symptoms, send a doctor to their home," Mathe told Continental radio. "The fear is unfounded. There is more fear than actual cases."

That fear isn't limited to the capital. On May 22, police in a city near the Chilean border fired rubber bullets to disperse a small group of people who pelted a bus with rocks and sticks after hearing rumours that a man on board was infected with swine flu. One protester and six officers suffered minor injuries after the protesters surrounded the bus at a provincial hospital in Godoy Cruz. The Chilean passenger was later determined not to be infected.

Chile has by far the most confirmed cases in South America, with 1,694 people sickened. But Chile's Health Ministry said just 29 are considered serious cases, and only two patients have died.

U.S. Centers for Disease Control and Prevention experts were arriving Wednesday to study the disease's spread in the nation, Chilean Health Minister Alvaro Erazo said.

Swine flu cases have been confirmed across nearly all of South America.

On Tuesday, Colombia announced the first fatal case within its borders: a 24-year-old who died last week in a hospital outside Bogota.

In Mexico, which initially bore the brunt of the outbreak, the health secretary said Wednesday that the country was no longer seeing serious cases.

Jose Angel Cordova said the number of new cases has fallen to less than 30 a day, down from a daily average of 300 at the peak of the outbreak in late April.

He said Mexico had confirmed a total of 6,337 cases of swine flu since the outbreak, including 108 deaths.

Cordova said he was concerned other countries now dealing with outbreaks have not taken such drastic measures as Mexico, which closed schools and restaurants for a week at the end of April to contain the spread of the virus.