A 30 foot section of a wall 20-30 feet high came down onto the pavement and road below at around 8pm.
It is not thought that anyone is trapped beneath the rubble, but the Fire Brigade are using thermal imaging cameras as a precaution.
Due to concerns that further sections of the wall may collapse officers are looking to evacuate approximately 40 elderly and vulnerable residents from 36 flats.
More heavy rain and strong gusts will sweep across Britain this weekend, with further floods expected in the UK.
ITV News viewers have been emailing photographs of flooding in their area over the last few days.
Torrential rain expected in South West England, South Wales and South West Scotland.