The sound of the safety clicking off seemed to echo ominously in the cavern.

The hum from the rifle's power unit echoed ominously.

Inside the 80-foot-long cave our voices echo ominously as he points out with some pride the new ventilation ducts and electric cables.

Destroy me, he echoed ominously in the human's mind.

The woman chuckled, a low, throaty laugh that echoed ominously in the dank darkness.

The word "involved" echoed ominously in his head.

The words echoed ominously in his brain, obliterating the possibility of any other thought.

One of them spoke - another woman, her voice echoing ominously.

The tramp of nailed boots echoed ominously up the stone stairwells.