Woman dead and two children missing after getting into trouble

A woman has died and her two children are still missing after the trio were spotted struggling to stay afloat in river rapids on Saturday.

Emergency services were called to a boat ramp on Floyd Bay in Lansvale, in Sydney 's south west, at Georges River at 10.15am on Saturday.

Witnesses reported seeing a woman and two children in the water in distress.

Paramedics were able to pull the woman from the water a short time after they arrived but could not revive her and she was pronounced dead at the scene.

A massive search is now underway for the two children.

Multiple agencies including Police, Marine Area Command, PolAir and SES have teams scouting the area for the children who are believed to still be in the water.

A report will be prepared for the information of the Coroner in regards to the woman's death.

Anyone with information about relating to this incident is urged to contact Crime Stoppers on 1800 333 000.

More to come