By Emma Young
A 24-year-old man has died at popular Lake Leschenaultia near Chidlow after reportedly having a seizure in the water in front of horrified swimmers.
The lake was packed with people enjoying the New Years Day public holiday on Monday just after midday when the man, who reportedly had a disability, went under.
The man, who was at the lake with a group of friends and carers, was gone less than a minute when people raised the alarm, 9 News Perth reported.
"He kind of just went underwater and my sister said to me, 'where's he gone?' a young witness told the station.
The lake was packed with people enjoying the public holiday. Credit: Nine News Perth
"I stood up and ... then he was being dragged out of the water by about four teenagers."
St John Ambulance received an emergency call at 12.09 and were on the scene at 12.18, a spokesman said.
Witnesses were performing CPR meanwhile with the call-taker instructing, and paramedics then carried on. They also used a defibrillator from the kiosk at the lake, to no avail.
Mundaring Police have launched a joint investigation with the coronial investigation squad.
Police are seeking witnesses to the incident and ask that anyone who has information to call Crime Stoppers on 1800 333 000 or make a report online at www.crimestopperswa.com.au.