The Shimmer by David Morrell

Costigan, seeing that the police chief had drawn his pistol and was crouching tensely, just as Page was.
    The chaos of the crowd now shielded the man with the rifle, and for a moment, he was lost from sight.
    Crack. Another muzzle flash projected toward the darkness.
    "You're all damned!" But the gunman was no longer yelling toward whatever had entranced them. Instead he turned and began yelling at the crowd. Page had the sickening realization of what was about to happen.
    No!
    The man fired directly into the crowd. People screamed and smashed against one another, desperate to escape.
    A man tripped.
    A woman wailed.
    Then Page realized that the man hadn't tripped. A bullet had dropped him.
    The gunman fired yet again.
    Page had seldom felt so helpless. Even if he'd had his pistol, the darkness and the commotion would have prevented him from getting a shot at the man with the rifle.
    Crack. A woman fell.
    Crack. A teenaged boy toppled. The crowd's frightened shouts became so loud that Page almost couldn't hear the rifle. He saw the barrel swing in his direction.
    Tori! he thought desperately. Pivoting, he ran toward the observation platform. Costigan was no longer in sight, but Page didn't have time to figure out what the police chief was doing.
    Tori!
    She was on her feet, so overwhelmed that she didn't have the presence of mind to react. Page had taught her about firearms and had asked her to keep a handgun in her purse. He'd worried about her taking clients out to remote locations where she'd be alone with them, but Tori never carried the gun he'd given her. The truth was, although she was a police officer's wife, her attitudes were those of a civilian.
    He put an arm around her and gripped her tightly, rushing her off the platform. Behind him, a bullet hit a board in the back wall. When she cried out in alarm, he pushed her head down, making her stoop as he rushed her around the corner. This was the side opposite from where Costigan had parked the police car, but Page was relieved to see that vehicles were parked here as well, and he tugged her behind a murky pickup truck.
    "Are you okay?" he asked, examining her as best he could in the starlight.
    She was too disoriented to answer.
    A shot echoed from beyond the observation platform.
    "Tori, answer me. Are you hurt?"
    His abrupt tone made her flinch, bringing her to awareness.
    "I . . . No. I'm okay. I'm not hit."
    "Thank God. Stay here. Keep behind the engine. Bullets can go through the truck's doors, but not through the engine. If you think the shooter's coming in this direction, fall down and pretend you're dead."
    In the shadows, she stared at him.
    "Tori, tell me you understand."
    Beyond the observation deck, two shots were followed by a scream.
    She blinked repeatedly. "Keep behind the engine," she said, swallowing. "If he comes this way, I'm supposed to fall down and pretend I'm dead."
    Crack. The gunman fired again.
    "I can't stay with you," Page said. "I need to help stop him."
    "Why is he doing this?"
    "I don't know why people do anything."
    The next shot Page heard was a loud pop rather than a crack. A pistol. Costigan must be returning fire, he decided.
    He squeezed Tori's shoulder and ran from the cover of the pickup truck. At once he heard another pistol shot, then a rifle shot.
    And a groan. Its raspy edge left no doubt that it came from Costigan.

    Chapter 20.
    The turmoil of his heartbeat contrasted with the slowness he forced upon himself when he reached the corner of the wall. His hands trembled. He fought to control them.
    The wooden planks of the wall couldn't protect him from an AK-47's high-powered bullet, but at least they concealed him as he crouched beneath the shooter's eye level and peered around the corner.
    The faint light from the opposite side of the observation platform showed him a nightmare. Bodies lay all around. Some twitched, but most remained still.
    The shooter stalked among them.
    "Came from hell!" He fired down at a head, his