After activating a fire alarm due to smoke, which action should the nurse take next?

The most appropriate action to take after activating a fire alarm due to smoke is to remove sources of oxygen near the fire. This step is critical because oxygen fuels fire. By eliminating oxygen sources, the nurse can help to reduce the intensity of the fire and prevent it from escalating, thereby protecting both patients and staff.

While evacuating patients and calling for backup assistance are important steps in fire safety protocols, they should follow the immediate action of addressing any potential oxygen sources that could exacerbate the fire's spread. Locating the source of smoke can be a dangerous action, especially in the presence of potential fire; the priority should be on ensuring safety first and controlling the situation before taking further actions.