Oppsagt uten saklig grunn

Employer terminated verbally our job contracts without notification before 14 days. Two of my colleagues are still on sick leave. One sick leave ends on 10.02 another on 24.01. The probationary period 3 months and notice period 14 days. Employer only told me, that I had one fault at the first week, but then I fixed it and worked without faults. And it's the "reason" he doesn't need to warn before. Under what conditions he may do this? Must he pay for these at least 14 days and for sickness?