A major incident has been declared in Hawick as persistent heavy rainfall could “result in significant damage to properties” in the Scottish Borders town.
The local authority said the situation affecting the River Tweed and the River Teviot is “worsening rapidly”.
Up to 500 properties could be affected, with projections by the Scottish Environment Protection Agency indicating the Teviot will peak above 3m at around 4pm on Thursday afternoon.
Scottish Borders Council said the situation also posed a risk to public safety.
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Chief inspector Vinnie Fisher, local area commander for the Scottish Borders, said: “We have been monitoring the situation with the weather in the Borders closely as the day has progressed and we have now made the decision, alongside our partners, to declare a major incident and have begun evacuating various residents around the River Teviot from their properties.
“We are working with our colleagues at the Scottish Fire and Rescue Service and Scottish Borders Council to safely move all of those affected and ensure they are appropriately accommodated for the time being.
“I would urge the public to avoid travel within the region unless absolutely necessary and to pay attention for more information as we continue to respond to this matter.”
Scottish Borders Council, Police Scotland, NHS Borders and Scottish Fire and Rescue Service took the combined decision to declare a major incident in Hawick, which will be led by Police Scotland.
Trinity Primary School and Hawick High School have both closed, with pupils and staff being sent home.
NHS Borders has closed Teviot Health Centre and the local authority has reopened the rest centre at Teviotdale Centre to provide assistance to those displaced by flooding.
Plans to evacuate residents and businesses likely to be affected are being activated.
Area commander Stephen Gourlay, the Scottish Fire and Rescue Service’s local senior officer for Midlothian, East Lothian and the Scottish Borders said: “We are supporting a multi-agency partnership response to prepare for a significant flood alert affecting several areas of the Scottish Borders including Hawick, Peebles and Newcastleton, issued earlier today.
“Following an official request from Police Scotland to support evacuation efforts in Hawick, Operations Control has mobilised four fire appliances to the Hawick area and an additional water rescue unit has been mobilised as a precautionary measure.
“We are currently working alongside partners to help ensure a safe evacuation of at-risk properties and will remain in attendance for some time.”
Scottish Borders Council said the flooding situation in Peebles is also very serious and all schools in the area closed early on Thursday afternoon where transport arrangements permit.
Motorists and rail passengers are facing major disruption due to flooding across the west of Scotland.
Several train services were cancelled or delayed due to torrential downpours on Thursday.
ScotRail say the main routes affected are: Edinburgh to Glasgow Central via Shotts, Edinburgh to Glasgow Queen Street via Falkirk High and Glasgow Queen Street to Alloa/Aberdeen/Inverness.
The Met Office has issued a yellow warning for southern Scotland and South Lanarkshire which has been extended until 6pm on Thursday and also now covers Strathclyde, Central Scotland, Tayside, Fife and the Lothians.
Traffic Scotland also encouraged drivers to take care while weather warnings remain in place across parts of the country.
Scotland’s transport minister Graeme Dey said: “The conditions could potentially bring disruption to the trunk road and rail networks, so it’s important people plan their journeys before they set off.
“Motorists should make sure their routes are available, follow travel advice from Police Scotland and drive to the conditions. The Traffic Scotland Twitter page is regularly updated and the mobile website – my.trafficscotland.org – lets people access the latest information.
“If you are planning to travel by rail, please check with your operator ahead of your journey. This is particularly important for cross-border travellers following the earlier disruption to services.”