Declare defenders then tap

[Mattao19]

Say my opponent attacks with a  {Lightning Mauler} (2/1) and I block with my  {Arbor Elf} (1/1) and after I declare my blockers I tap my Elf to untap a forest. Does the Elf still deal/take the 1 damage?

[MementoMori]

Yes. Tapping doesn't remove the creature from combat.

[Mattao19]

Yes. Tapping doesn't remove the creature from combat.

So both creatures die right?

[MementoMori]

Yes.