John Gill Commentary 2 Samuel 2:16

"And they caught every one his fellow by the head, and [thrust] his sword in his fellow`s side; so they fell down together: wherefore that place was called Helkath-hazzurim, which is in Gibeon." — 2 Samuel 2:16 (ASV)

And they caught everyone his fellow by the head
By the hair of his head with his hand:

and [thrust] his sword in his fellow's side ;
which he had in the other;

so they fell down together ;
the twelve on each side, all the twenty four; some think only the twelve on Abner's side fell; but to me it seems that they all fell dead as one man, since they thrust their swords in each other's sides:

therefore that place was called Helkathhazzurim, which [is] in Gibeon ;
the field of rocks, or of mighty men as strong as rocks, who stood as immovable, and would not give way, but fell and died in the field of battle; the Targum interprets it, the inheritance of the slain.