Take evasive action
Definition 1 of 1
Pro Tip 1/3Urgency Implied
Suggests immediate action. When someone takes evasive action, they act without delay. 
The presence of smoke caused the crew to take evasive action.
Pro Tip 2/3Danger Averted
Action is to avoid a potential hazard. It is a response to an imminent threat. 
To avoid the collision, the cyclist had to take evasive action.
Pro Tip 3/3Quick Reflexes
Often involves instinctive reactions. It's not preplanned but a spontaneous response. 
The hikers took evasive action when they stumbled upon a bear.