Rick made a really dumb decision killing Primo. From what the redheaded lady said, they're ALL Negan, i.e. they all represent him as members of the gang. They should have interrogated him...everybody talks, eventually. Big mistake, and it's going to catch up with them at the end of the season. At the very least, they should have cleaned up the bodies at both sites to cover their tracks...
It's really unusual for Rick to be so short-sighted. He knows there are multiple gangs & doesn't know how many resources they have, people & otherwise, and why they all act the way they do...despite Rick being covered in blood half the time, even the Alexandria townspeople don't all agree or stand with Rick, so they have some crazy gang loyalty going on with Negan's people.