Emergency authorities said they carried out 13 rescues and received 297 calls for assistance from residents in Sydney, the capital of New South Wales state, in the 24 hours to 5am local time, because of floods sparked by the heavy rain.

Ten emergency evacuation orders were in place for suburbs in the city’s northwest, the New South Wales State Emergency Service (SES) said in a statement on Saturday morning.

The nation’s weather forecaster warned that major flooding could occur in the northwest of Sydney, a city of about five million, later on Saturday.

Sydney’s Hawkesbury-Nepean valley is a floodplain prone to dangerous flooding, as it is fed by five tributaries and has chokepoints limiting flows to the sea, so water backs up during heavy rain.

SES’ acting assistant commissioner Dallas Burnes told the Australian Broadcasting Corp. that there was “still a lot of water moving around” and urged affected residents to be prepared to leave their homes.