I probably became more aware of this area of prayer during the time my husband Don was on a volunteer fire dept/rescue squad when we lived in Nebraska. When the pager went off or the fire siren was activated, I would try to pray for the entire situation. It is amazing how many people you can pray for when you hear a fire, police, or ambulance siren wailing down the street. You know someone is in trouble so you can pray for the person/family in the middle of the need as well as the safety and wisdom of the responders, any witnesses, emergency personnel at the hospital, etc. You might just settle on one angle and cover that group in prayer.
Using emergency sirens as a trigger has been helpful to me. Now that I live in a bigger city, I find that I have the occasion to use that cue more frequently.
Emergency Siren= Someone is in trouble= Pray
I am always amazed how God uses daily things to get my attention. Lord, increase my awareness!