A 21-year-old college student from Minnesota has been arrested on Interstate 80 in Nevada 50 miles from Reno and charged in connection with the mailbox pipe bombings. Luke Helder’s enrolled at the University of Wisconsin-Stout, but his parents still live in Pine Island, Minnesota. He was caught after the FBI put out a nationwide alert Tuesday morning naming him as a suspect in the case. Helder’s dad read a statement yesterday urging his son to turn himself in. With Tuesday’s arrest of Helder, the U-S Postal Service is resuming normal deliveries. Postal Service spokesman Richard Watkins says it’s okay now for people to shut the doors on their mailboxes, following the placement of 18 bombs in five states, including five bombs in eastern Iowa. Seven people were injured in Iowa and Illinois Friday when the pipe bombs placed in the rural mailboxes exploded. Watkins says authorities are sure all the bombs allegedly placed by this suspect have been found.Watkins says the arrest should close the case, but he urges customers to remain vigilant, be alert and report anything suspicious to the authorities. He thanks Iowans for their understanding and cooperation in the past few days.Watkins says with the help of Iowans keeping their mailbox doors open, 98-percent of the mail was delivered statewide on Monday, the post office’s busiest day, and 99-percent was delivered Tuesday.