ABILENE, Texas — Six airmen and three of their relatives have been quarantined in Texas after some reported respiratory problems similar to SARS, officials said.

A group of military personnel passed through the Toronto airport recently, and some reported mild to moderate respiratory problems earlier this week after returning home, said Capt. David May of Dyess Air Force Base in Abilene.

Only one person in the group fits the definition of a suspected SARS case, and no one has been officially diagnosed with SARS or been hospitalized, May said. But he said nine people are now quarantined in their homes.

Officials with the Abilene-Taylor County Public Health District said Thursday that there is no reason for alarm.

Federal officials lifted a SARS-related travel alert for Toronto on Tuesday. The Centers for Disease Control and Prevention said more than 30 days had elapsed since the last SARS case in the Canadian city developed symptoms. The CDC said it would monitor the situation in Texas.

Members of the SARS containment team in Toronto expressed frustration today at the developments in Texas.

"The chances of this being SARS are almost beyond calculation," said Dr. James Young, Ontario's commissioner of public security. He suggested public health officials should be cautious about raising alarm about unconfirmed cases of SARS, considering the economic consequences of such reports for Toronto.

Last week, the World Health Organization said SARS, or severe acute respiratory syndrome, had been contained. More than 800 people worldwide have died of SARS since the outbreak began in Asia late last year.