IOWA CITY, Iowa — Authorities say an 18-year-old student who collapsed in a University of Iowa residence hall died of drug intoxication and complications from a heart condition.

Sean Wu, of Cedar Rapids, was pronounced dead April 8 at a hospital. A witness told authorities that he saw Wu suddenly tense up at Daum Residence Hall “as if he were having a seizure and collapsed.”

The Johnson County medical examiner’s office says the drug Ecstasy was in Wu’s body. The synthetic drug can induce euphoria and increase the heart rate. Wu’s family also says he was diagnosed with Kawasaki disease when he was 6, a condition that causes inflammation of some blood vessels.

The university says its investigation of Wu’s death is continuing.