Vicious ghosts

Utmost emergency!! Was that even possible? What to do now? As the beasts kept tracking him with their screeches. The pain was slightly subsiding, however Dan was, yet, feeling dizzy. He stopped, panting, his legs trembling.

What to do? What to do now? Keep on running? He felt out of breath, and out of strength.
Hide? Could it be done?
Attack, then? Those monsters had swayed away from his bullets like nothing; obviously the shots only wounded them slightly. Extreme nervous tension.
Dan, swearing like a drunk fool, tried to think something up. Fast.
He glanced across the warehouse; the windows were located high above his head, and the door looked like it was nailed shut. It was hopeless.

His back ache smouldering. He had been.... hit. By something, that was fired at him by that monster. The raised arm, pointing to his lower back.
In a swift motion, he felt his kidney area with the left hand and brought it again to observe it. Blood. His own! He had a cut. What had cut him? He took his hand behind, to his back, again and upon inspection, touched a small spheric object, tucked in his shirt; indeed small, with the size of a pea....

And with those high-pitched squeals, the creatures made themselves center stage; there they were, having followed the same alley way (which was circumscribed by the research center at its right side, and by convenience shop with small twinkling bulbs at its left) that Dan had come from.
Lifting their arms and revealing their jagged claws, menacingly, hinting at their awful intentions. Some 20 meters (66 feet) separating them from their target. Slowly, inexorably coming closer. Dan hoisted himself and pointed his weapon at them, trying to appear resolute: an ordinary advice used to frighten animals that he had always heard of was to be able to convey a fierce look.

It wasn't working as he expected. Nothing whatsoever was convincingly.
A further, more 'open eyes' analysis would also reveal to him that their heads didn't have eyes, or nose, or even skin. What they had for a head seemed to be an inflated, sangria coloured bulge, which could only be the brain. The lower part of the bulge was covered by some pleats that formed what resembled a sagged cleft. It would equate to the mouth.

He fired, again. Three times. However, the beasts were ready As the gun was blazing, the creatures seemingly vanished into thin air (like phantoms made of ether), only to appear, almost at the same time, some three feet (92 cm) sideways of their original spot. Unheard of. It was as if they had miraculously 'displaced' themselves away from range, and - it was crazy - they were untouched. They were gone, and then back, in the same instant.
Dan fired again. One shot, and another, and another. The things repeated the same trick.

The monsters were, that way, closer to the pedestal uplifting the statue of a flag-holding man, mounting a horse, located near of the center of the square. Dan kept pressing the trigger of a empty gun. Only the "click" sound of the hammer punching the pin as the Beretta had no more bullets.
About 10 meters (33 feet) in distance, now. Dan fell to his knees. He no longer smothered screams and cried for help. He was done in for.
Then, out the nowhere, that particular statue came to life and began moving, rotating almost 180 degrees from its initial position, so that it was facing "them" now, as it (the Prussian represented in the statue) made its flag slide down. Dan couldn't believe his eyes.

The tip of the flag pointed at the beasts and fired, with resonance, a projectile.
Upon contact, a sudden, enclosed but massive explosion threw Dan some feet backwards and reduced the beasts to glowing pudding; with a shattering final screech, those things were now combusting in smouldering flames.
Dan had witnessed, without being fully aware of it, the destructive power of an useful, albeit unexpected, aiding weapon: a concussion grenade. How did it happen, though?