The bomb threat later proved to be a bad joke, hatched by a student on social media, that forced OSU to err on the side of caution, the tech company Starship, which operates the robots, said in a statement.
"A student at Oregon State University sent a bomb threat, via social media, that involved Starship’s robots on the campus," the statement said.
"While the student has subsequently stated this is a joke and a prank, Starship suspended the service. Safety is of the utmost importance to Starship and we are cooperating with law enforcement and the university during this investigation," it said.
The OSU warning was issued at 12:20 p.m. local time, and by 12:59 p.m., the potentially dangerous bots had been isolated at safe locations, the school said.
The robots were being “investigated by” a technician, OSU said in a statement posted at 1:23 p.m.
“Remain vigilant for suspicious activity,” it added.
Finally, at around 1:45 p.m., the school issued an “all clear” alert.
“Emergency is over,” the message said. “You may now resume normal activities. Robot inspection continues in a safe location.”
Starship calls itself a “global leader in autonomous delivery” with agreements at a host of universities across the U.S.