Before answering!!! **ImageLabel doesn't change color when supposed to on wait time if there are multiple imagelabels with the same script. **
local Redblink = script.Parent
local speed = 0.2
while true do
Redblink.ImageColor3 = Color3.fromRGB(255,0,0)
wait(speed)
Redblink.ImageColor3 = Color3.fromRGB(255,255,255)
wait(speed)
Redblink.ImageColor3 = Color3.fromRGB(255,0,0)
wait(speed)
end

4 comments
Any errors? Do the image labels have different names?
No, thay do not. Should it? @antonio6643
Personally, I find lerp to be better, my opinion though. http://wiki.roblox.com/index.php?title=Lerp
If a LocalScript, containing the code you've provided, is a child of each ImageLabel you're trying to affect, all ImageLabels will flash between red and white simultaneously. I just tried it and it worked fine. If you're desiring a different result than what I just described, please be more clear in your question.