Mating Center by Frank Belknap Long

The explosion came abruptly, shaking the entire room, hurling Teleman to his knees and sending the man and the woman staggering backwards. It did not come from within the room, but from somewhere in the forest outside the house. But close, close. Teleman could feel its nearness in his bones, the shock waves and the concussion, as the thunder of it roared in his ears, half-deafening him, and a bright burst of accompanying flame danced and flicked on the vibrating panes of the window.

For an instant the panes continued to vibrate and then, abruptly, the glass was shattered and fell in tinkling fragments to the floor. But one of the spinning fragments was hurled with such violence from the window's upper frame that it did not drop to the floor. With the speed and flashing brightness of a tiny, keen-bladed spear, thrown with a deadly accuracy of aim, it went flying through the air to bury itself in the woman's chest, just above the heart.