The property arm of Vancouver-based Jim Pattison Group did not know that the Virginia warehouse it owns was intended as a U.S. Immigration and Customs Enforcement holding facility at the time it agreed to sell the site, the firm said in a statement on its website. Jim Pattison Developments said it publicly listed the site for lease or sale and accepted an offer from “a U.S. government contractor” to buy the property. The looming 550,000-square-foot industrial warehouse, surrounded by a fresh layer of snow and ice from a weekend blizzard, was inaccessible Wednesday, with its entrances blocked. The small county’s consideration of the sale comes amid an immigration crackdown in the United States. Jim Pattison Developments, owned by British Columbia billionaire Jimmy Pattison, said in the statement that it would not normally comment on a private transaction.