The 25-year-old officer has been taken to hospital in a serious but stable condition.
A NSW Police spokesperson said the attack took place around 7pm at the station in Haymarket, and the officer’s injuries are not believed to be life threatening.
In a statement, NSW Police said the man allegedly approached officers from the Police Transport Command and stabbed a male senior constable in the back.
Two other police officers ran to their colleague’s aid, where a struggled with the offender ensued.
The officer is currently being treated at Royal Prince Alfred Hospital.
The 53-year-old alleged attacker is believed to have sustained a cut to his head during the arrest and has also been taken to hospital.
His condition is unclear.
A crime scene has been established at the platform, which will be forensically examined.
The matter does not appear to be terror related.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000.
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