How Can I Write My Novel In First Person If, The Main Protagonist Has Amnesia?

In this story the main protagonist is hit hard on the head with a fire extinguisher resulting in him being knocked unconscious and also gets amnesia due to it, and the story is in first person. I need some way I can carry the story forward when the protagonist regains conscious, now the problem I'm having is that if the person has amnesia he's probably isn't going to remember anyone and therefore I'll probably have to say something like, a woman stood there no further than a couple of metres away ect... and nobody's going to know who she is because if the protagonist doesn't know then the reader won't know and everyone's going to get lost, so what would be the best way to write something like this? Would it be to describe the characters or still say who the people are so people don't get lost? Or do I get the other characters to tell the protagonist? Like for example the protagonist asks who they are and they tell him.