The search for a father and son who went missing after their car crashed into a river north of Sydney has come to a tragic end, with two bodies found by divers.

Police had been searching for the two men after the car they were travelling in crashed into the Macdonald River, near Settlers Rd in St Albans about 11.50pm on Wednesday.

A second son also in the car managed to escape and reach the riverbank.

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The man in his 20s was assessed by paramedics but did not need any further treatment.

It is believed the car had crashed into a tree before plunging into the river.

SES, NSW Rural Fire Service crews and police are still searching for the second man.

Anyone with any information about the missing men should contact Hawkesbury Police or Crime Stoppers.