Swallow nests predated

I have just found that the three swallow nests up in my eaves have been predated. I noticed broken pieces of nest wall on the ground, then found a dead chick. When I looked up at the nests all three had been smashed (two had live chicks in prior to the attack) I can only assume this is another bird as the nests are about 6 metres off the ground. 

Is this common, not found anything obvious on internet searches?