MELBOURNE, Australia (AP) — Four people have been confirmed dead from a rare condition known as thunderstorm asthma that sent hundreds to hospitals in Australia’s second-largest city.

Family confirmed on Wednesday that Clarence Leo had died at home early Tuesday morning after the wild thunderstorm in Melbourne on Monday night. It caused rain-sodden ryegrass pollen to explode and disperse over the city. The pollen caused asthma attacks in patients who had never suffered from asthma before.

Ambulance Victoria spokesman Mick Stephenson reported a six-times larger caseload because of the asthma attacks. One ambulance company responded to more than 1,870 cases.

Professor George Braitberg, head of the Royal Melbourne Hospital’s emergency department, likened the scene in the hospital on Monday night to a war zone.

He says seven asthma patients had been transferred to the hospital’s intensive care unit.