Increased Pressure and Ticking Clocks, Failures and Mistakes, Duty and Responsibility, Loss of Control, No-Win Scenarios

Trying to rescue family members from a burning building
Arriving on the scene of an accident where multiple people have critical injuries and being unable to get to them all
Rescuing people who are drowning after a boat capsizes
An opportunity to liberate people in captivity but being unable to free everyone
Having a transport which can save some from a war zone or other imminent threat, but having limited seating
Sniping from a distance to support ground troops, but being unable to take out every enemy
Having two threats happening at the same time, and being forced to choose one to respond to (two bombs needing to be diffused, synchronized attacks happening on two different battle fronts, etc.
Coming across multiple people with the same illness, condition, or poisonings, and having only enough medicine or antidotes to help some

Remaining objective when faced with having to choose who to save when there are people the character knows
Having to choose between people the character cares about equally
Becoming paralyzed by the enormity of the situation and inactivity causing further challenges or risk
Having to reason with others who are involved and try to get everyone working together to save as many as possible
Arguments with others over who to save and why (if the threat isn't immediate where they have no time to think, only act)
Increased risk and danger to the character and those they are trying to save as the clock ticks down
Unshakable guilt and remorse
Damaged relationships and the anger of others due to the choices one made