What was happening ...?
Past Continuous
Use the past continuous to express what was occurring at a precise moment in the past. The past continuous is often used together with the simple past to express an interrupted action. The action which was interrupted is expressed using the past continuous, while the action which caused the interruption takes the past simple.
Positive Form:
Subject + to be + verb + ing + objects
The Chicago branch of our restaurant business was struggling when Brando called.Negative Form:
Subject + to be + not + verb + ing + objects
The cruise ships weren't sailing when the storm arrived.Question Form:
Wh? + to be + subject + verb + ing?
Were the customers buying from the self-service vending machines when the cafeteria opened?