Striking them with stones of Sijjil.
It is reported from Ubayd bin Umayr that he said,
"When Allah wanted to destroy the People of the Elephant, he sent birds upon them that came from sea swallows. Each of the birds was carrying three small stones -- two stones with its feet and one stone in its beak. They came until they gathered in rows over their heads. Then they gave a loud cry and threw what was in their claws and beaks. Thus, no stone fell upon the head of any man except that it came out of his behind (i.e., it went through him), and it did not fall on any part of his body except that it came out from the opposite side.
Then Allah sent a severe wind that struck the stones and increased them in force. Thus, they were all destroyed."
Concerning Allah's statement,
فَجَعَلَهُمْ كَعَصْفٍ مَّأْكُولٍ