A crocodile has left a man in his 60s injured after attacking him while he was swimming in a popular lake in WA’s North on Friday afternoon.

Three people who tried to help the man, were also bitten.

Emergency services attended Lake Argyle with St John paramedics rushing the man to Kununurra Hospital under lights and sirens.

He remained in hospital on Saturday where he is being treated for multiple non-life threatening injuries and is in a stable condition.

The others involved were treated at the scene.

The West understands his bites are consistent with a fresh water crocodile.

Freshwater crocodiles are known for being less aggressive towards people making an attack like this very rare.

Despite the scare, the annual Lake Argyle Swim open went ahead on Saturday.

Four hundred swimmers hit the water taking on a modified course.