The chicks were part of a 12,000-bird shipment left unattended in a truck at a Delaware mail distribution center. Trapped in high temperatures without food or hydration, thousands died, according to the state Department of Agriculture. The U.S. Postal Service has said it is investigating the “process breakdown” that occurred.

A Delaware animal shelter is trying to care for and rehome thousands of chicks that survived being left in a postal service truck for three days. Trapped in a warm enclosure, without food and water, thousands died before they were discovered on May 2, CBS affiliate WBOC reported.

First State Animal Center and SPCA in Camden has spent the past three weeks caring for the chicks and finding homes for them.