FARGO (AP) - Seven North Dakota State University buildings were evacuated Tuesday after a duffel bag was found outside a campus bus shelter, NDSU officials said. Police said a robot was used to open the bag and nothing threatening was found.

A student reported later that he forgot the bag at the bus stop, Police Sgt. Jeff Skuza said.

Police and NDSU officials said they knew of no threats and figured the duffel bag likely was harmless, but in light of Monday's shooting rampage at Virginia Tech, they wanted to be careful.

"This certainly isn't the first unattended package that's been checked out in Fargo-Moorhead," NDSU spokesman Dave Wahlberg said. "But with the events of yesterday, it really enforces the need that if there's anything you can do to err on the side of safety, that's what we want to do and that's what we're doing right now."

Skuza said the bomb squad used similar procedures for suspicious items reported on three separate occasions in the last four months.

"I don't think Virginia Tech had any bearing on what happened today," he said. "This is a typical response to this type of thing."

Authorities earlier investigated packages found at a downtown bus depot, police headquarters and the federal courthouse. The package outside the courthouse was disguised as a bomb.

Skuza said the duffel bag was found about 1:30 p.m. Tuesday.