1. construction of house was in minority comminuity i.e. community was mostly muslim
2. family rebuilding a house there which was opposed by members of a community - looks like a Hindu bought a house there and was rebuilding it and it was opposed by muslims, who are a minority community but a majority in that community where the house was being built.
Are you confused enough?
So, Muslims clashed with the house owner. Then sensing it a communal issue, Hindus retaliated. Even Shiv bhakts going to Harwar (kaanwadia, I suppose) joined in.