Note: This is a classic neighbor looking after neighbor. The homeowner was aware of what was going on around their home and when they saw suspicious activity they called 911 in a timely manner.
Burglars are naturally risk adverse. They do not like to be observed. They want to steal where no one can see them, or at least be seen by anyone who calls police. After all they do not want to spend any time in jail. But calling 911 so that a deputy can respond increases the risk to burglars. So calling 911 when you see suspicious activity, or a crime in progress is as important as more passive measures such as posting Neighborhood Watch signs, keeping your landscaping trimmed so that your front door can be seen from the street, or installing deadbolt locks and using them.