An unidentified disease killed two high school students in the US state of Texas since March, officials said.

A third student was in critical condition due to same disease, local media quoted state health officials as reporting Thursday. The three students, all from the Houston area, shared similar pneumonia-like symptoms, including fever, coughing and later, seizures and respiratory failure, Xinhua reported. The first patient, aged 17, got sick in February and died on March 10. A teenage girl died on April 29 and a teenage boy with similar symptoms is currently in critical condition. The autopsy results won't be available for several months.