Use the past continuous steps with one event occurred first, which is in progress in the past and then have another event waiting in a short time, or events that are clearly at a certain time in the past.
Past continuous use when an event occurs first. Which was performed in the past Then there was another incident piled up in a short time, or event is in progress, clearly at a time in the past.
Use past continuous when an event occurred. The progress in the past. Then there is another event was piled up in a short time or event going be clear at one time in the past.