A bag containing suspicious contents and a video showing a person entering the University of Minnesota’s Coffman Memorial Union prompted authorities to close the building for a daylong sweep Monday.

Workers in the building noticed the bag on the first floor of the student center and notified campus officials around 11:30 p.m. Sunday. The building is a center of activity, housing the campus bookstore and dining area. But the building is closed on Sundays during the summer, so officials were suspicious.

By 4:30 a.m., officials called to investigate the bag decided to close the building for a more thorough search. Tim Busse, a university spokesman, said police were bothered by what was inside of the bag, which he described as an “athletic, or camping-style bag.” He would not elaborate further, citing the ongoing investigation.

“It was a contents of the bag that were a cause of concern, and they came up with some video images of a person entering the building, which was also concerning,” he said.

Busse said he could not answer questions about whether the person on the video had been located or is a student.

Police spent Monday using bomb-sniffing dogs to search the more than 330,000-square foot building, which was roped off with yellow police tape. Shortly after 3 p.m., campus officials sent out an alert notifying students and staff that the building would remain closed until 7 a.m. Tuesday.

Staff writer Paul Walsh contributed to this story.