A stand which became unstable during England's Twenty20 international against the West Indies, causing injuries to three spectators, passed a safety inspection last week, Durham said.
A small area of the of sold-out Emirates Riverside at Chester-le-Street was evacuated by stewards last night during the tourists' 21-run victory.
As play continued in the middle, pictures emerged on social media of what appeared to be a hole in a section of flooring.
The North East Ambulance service responded to a 999 call from the ground and took one of the three injured fans to the Royal Victoria Infirmary in Newcastle.
Twitter user @ChristianCeriso posted an image of two stewards standing guard either side of what appeared to be an opening directly beneath a seat.
Fans from the entire block were ushered away from the area and guided to other parts of the ground.
A club statement read: "During the course of the second innings between England v West Indies at Emirates Riverside, three spectators were injured when a small section of the North-East Terrace flooring became unstable, causing them to fall.
"Stewards took precautionary action and evacuated that area of the stand efficiently.
"The stand is a permanent fixture at the venue and had passed inspections in the week prior to the match."
Windies captain Carlos Brathwaite said after the match that some of his players felt conditions on the pitch were "unsafe", and was prepared to take an abandonment after wicketkeeper Chadwick Walton slipped while fielding, needing lengthy treatment.