A burst water main on the sixth floor of a block of city centre flats caused damage to around 26 apartments.
Fire crews from Farringdon, Sunderland central and a specialised unit from Gateshead were called to the City Green block, near Park Lane bus station at 7.30pm last night.
A burst water main in the communal area on the sixth floor saw up to four inches of water flooding down through the building.
Watch manager at Sunderland central station, Garry Teasdale, said it was quite frightening for the residents because of the huge amount of water coming down through the building.
He said: “When we arrived there was a huge amount of water cascading from the top floor down the stairs. It was alarming, there was a lot of water, it was quite shocking to see.
“We managed to isolate the leak and then set about pumping the water out of the building.”
The extent of the damage to the flats, which are owned by Gentoo, will be known once they have fully dried out.
Firemen and electricians had to isolate the electricity to parts of the building to make it safe for residents who wanted to stay in their homes last night.
Crews were on the scene for almost three hours helping to tidy up from the flood. They were using pumps, dehumidifiers and drying hoovers to dry out the building.
Mr Teasdale said: “It was purely an accident and nothing malicious. If is had been on the bottom floor there wouldn’t have been such a problem, but with it being on the top floor it was much worse.”
He said the top three floors suffered the most damage and the bottom three were not so badly hit.
Ian Porter, Executive Director of Property at Gentoo Group said: “We were made aware of a burst water valve in one of the corridor water riser cupboards last night and immediately sent staff down to City Green to assess and deal with the situation.
“The team stopped the leak and pumped out the water last night and remained on site to ensure residents were offered support and alternative accommodation for the evening if required.
“Gentoo staff are now on site cleaning up and getting all services back up and running. Ensuring residents are comfortable and have everything they need is our main priority.”