Something that I, lore wise, don't understand about scp containment breach and secret laboratory

I like to read about the MTF units and after reading about AMTF NU 7 Hammer down, it says that they also respond to multiple scp containment breaches which happens in both games and a chaos insurgency raid also happens and from what I read, Epsilon 11 is a quick reaction force but in this situation, i think they would have been relived or at least announced that they were going to be relived by NU 7 as they did in incident 5018.1, unless if NU 7 wouldn't have been deployed to the site first but still, NU 7 would have at least been on it's way when epsilon 11 reached the site so please explain it to me.