Valmiki Ramayana Yuddha Kanda Sarga 53 Shloka 18

ततः then, घोराणाम् dreadful, भीमरूपाणाम् fierce form, अन्योन्यवथकाङ् क्षिणाम् each one trying to kill another, हरीणाम् Vanaras, तथा in the same way, रक्षसाम् Rakshasas, तुमुलम् intense, प्रवृत्तम् encounter.

Then dreadful encounters of fierce form took place between Vanaras and Rakshasas each one trying to kill another.