Man critical after pulled from Sydney pool

A man was rushed to hospital in critical condition after reportedly hitting his head in a Sydney pool.

Emergency services were called to the Macquarie University Sport and Aquatic Centre at Marsfield about 2pm (AEDT) on Sunday.

CareFlight director Ian Badham said pool attendants found a man, believed to be in his 30s, in critical condition in the water.

"The pool attendant started CPR straight away and very effectively," Mr Badham told AAP.

People at the pool reported that the man had hit his head, he said.

It is believed the man was swimming by himself.

He was placed in an induced coma and rushed to Royal North Shore Hospital, where he remains in critical condition.

Police are now at the aquatic centre.