IRS Auction property

[Hung P.]

In an IRS auction, the IRS lien was recorded after the first mortgage.  Does the winning bid with the IRS eliminate the first mortgage and get the deed to the property after the redemption period or will they just eliminate the IRS lien and have to assume the first mortgage that was there before the IRS lien.  The mortgage is a small amount 1/5th of what the property is worth, while the IRS amount is over 250k+ (more than the property is worth).  TIA