EL PASO, Texas -

Could another empty lot be coming for downtown El Paso?

     ABC 7 first reported last week about a plan to demolish an entire city block made up of five buildings at the corner of San Antonio and Mesa street. Now, it looks like the wrecking ball is already swinging.

ABC 7 crews went to the site today, and one of the buildings on Mesa is already more than half gone. They haven't been working today, but over the past few days demolition crews have removed the majority of the back part of the building at 109 S. Mesa.

    The demolition apparently began over the last few days. Property developer River Oaks Properties received demolition permits from the city to knock down all five buildings in the block, and fences were put up soon after those permits came to light last week.

     Preservation groups are outraged about the plan and say that at the very least, the historic facades should be preserved.

     "With this lot, we're talking about the single greatest act of destruction, from a preservation standpoint in downtown El Paso, in more than a generation," said Max Grossman, vice chair of the El Paso County Historical Commission. "This lot will be truly immense, and will stand in front of several historic buildings, including Richard Caples and including the Popular Department Store. I don't think El Pasoans will fully understand the extent of the destruction until they see the gigantic empty lot that is going to be created."

     River Oaks, which owns the group of properties hasn't announced any specific plans for the property once demolition is completed. ABC 7 reached out to River Oaks again today, but haven't heard back, and their offices are closed for the Memorial Day holiday.

     Advocates for preservation are planning a protest for Thursday from 4:30 to 6:30 p.m. and are starting an online petition to save what's left of the buildings.