If you choose to have a few people die in the scene, it will elevate the scary feeling, but can turn your scene into a horror film, detaching your audience from reality, which can be good or bad, depending on what you desire.
A good way to create tension is using extreme close-ups. For example, if you are showing a person running, just show the feet hitting the ground. Also, focusing on the eyes brings the audience closer to the actors. Expressiveness in the eyes can create feelings of fear, tension and suspense.
Lighting is key in creating suspense. Use dramatic lights and darks to add tension in your scene. Black shadows, bright disorienting lights and sharp contrasts can add interest to your movie.
Music is key when heightening the tension. Watch any Alfred Hitchcock movie and the music alone will send shivers up your spine. Low, booming bass works well, but high-pitched, shrill sounds are the best.
Try to use as few shots and cuts in the scene as possible, so there is little gap between the action. This also gives the feeling that you are actually there witness the action, and can easily build tension in a film.