2 Chronicles 23:12

Now when Athaliah heard the noise of the people running and praising the king, she came to the people into the house of the LORD:

When Athaliah heard the noise. The unusual commotion indicated by the blast of the trumpets, and the vehement acclamations of the people, drew her attention or excited her fears. She might have flattered herself that having slain all the royal family, she was in perfect security; but it is just as likely that, finding on reflection one had escaped her murderous hands, she might not deem it expedient to institute any inquiries; but the very idea would keep her constantly in a state of jealous suspicion and irritation. In that state of mind, the wicked usurper, hearing across the Tyropoeon the outburst of popular joy, rushed across the bridge to the temple ground, and penetrating from a single glance the meaning the whole scene, raised a shriek of "Treason!"