(DALLAS, AP) — Texas Gov. Rick Perry says a handful of school-aged children who had contact with a man diagnosed with Ebola are being monitored.

Perry says health officials learned Wednesday that the children have been identified as having contact with the man and are being monitored at home. The unidentified man has been in isolation at Texas Health Presbyterian Hospital in Dallas since Sunday.

The man is the first person to be diagnosed with Ebola in the U.S. Health authorities have not revealed his nationality or age. He was listed in serious condition Wednesday.

Authorities say the ambulance crew who transported the man and members of his family are among the 12 to 18 people being monitored after exposure to the man.