What is the difference between "Ajirna" and "Ajirni"?

I don't know Arabic very well. Our imam in the mosque says "Allahumma Ajirna Minan Naar" and we say "Ameen" to it. Now due to lockdown, I hear to radio more often and I noticed that the Imam in the radio says "Allahumma Ajirni Minan Naar " Is there a difference between the two ? I asked my teacher but she was also confused.She said that the latter is the correct one according to her knowledge. Please explain