Even as Rāvana charged, the sun became dim and the four quarters were enveloped in gloom. Birds shrieked hideously and the earth shook. Clouds rained blood and a meteor fell from the sky with a crash. Rāvana felt his left eye twitching and his face became pale. A large vulture perched upon his standard and crows circled above him.
Not minding these fearful omens, Rāvana careered madly toward the massed ranks of the monkey army. He plunged into them, immediately creating havoc. With arrows decked with gold he severed the heads of thousands of monkeys. Others were pierced in the heart and still others had their limbs lopped off. Some were crushed by his chariot and some smashed by his mace. Wherever his chariot moved, the monkeys could not stand and face him. An irresistible hail of arrows flew in all directions from Rāvana’s chariot. He was as hard to approach as the scorching sun.
Soon the battlefield was strewn with the corpses of slain monkeys. As Rāvana ploughed into the Vanara forces they fled, tortured by his weapons. The demon king dispersed the simian ranks like the wind dissipating clouds. Having cut through the monkeys, Rāvana searched for Rāma.
SOURCE: Valmiki Ramayana as retold by Krishna Dharma Dasa, Bhaktivedanta VedaBase: A Treasury of Spiritual Knowledge