NEWTOWN, Conn. — While the people of Newtown do their best to cope with loss and preserve the memories of their loved ones, another class of residents is also finding it difficult to move on: the emergency responders who saw firsthand the aftermath of last week’s school shooting.

Firefighter Peter Barresi was driving through Newtown on Friday when police cars with lights flashing and sirens blaring raced toward his oldest son’s elementary school. After he was sent to Sandy Hook school himself, he saw things that will stay with him forever.