Valmiki Ramayana Aranya Kanda Sarga 30 Shloka 28
Original Shlokaस वृत्र इव वज्रेण फेनेन नमुचिर्यथा। बलो वेन्द्राशनिहतो निपपात हतः खरः।।3.30.28।।
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सः खरः that Khara, हतः killed, स वज्रेण by the thunderbolt, वृत्र इव like Vrutra, फेनेन by froth from, नमुचिः Namuchi, यथा like that, इन्द्राशनिहतः struck by Indra's thunderbolt, बलो वा like Bala, निपपात fell down.
Khara fell down just like Vrutra or Bala killed by Indra's thunderbolt or like Numuchi by the froth of the sea.