A Border Patrol agent was missing Tuesday night after attempting to rescue a Chinese illegal alien from the Colorado River, officials said.Several law enforcement agencies were searching the river for the agent Tuesday night. He was swept away by the rivers current as he tried to pull the alien to safety around 6:30 p.m., said Border Patrol spokesman Joe Brigman.The agent, whose identity was not released, had not been found as of 9:30 p.m. Tuesday.During a routine check of the river near Andrade, Calif., Border Patrol agents discovered approximately seven illegal aliens, Brigman said. The group had crossed the river...