Officials are investigating who was responsible for bomb threats Friday that evacuated North Dakota State University in Fargo and the University of Texas in Austin.

FBI spokesman Kyle Loven said officials are trying to determine whether the threats were linked. A phone call to NDSU around 9 a.m. Friday warned of a bomb on campus, and a similar call was placed to the University of Texas at Austin at 8:35 a.m., Loven said.

"It is a little too early to determine if there was a connection," Loven said. "We will follow any investigative leads."

No bombs surfaced at either campus, authorities said. By 2 p.m., NDSU resumed classes. Texas reopened its buildings at noon.

No other Fargo area schools, or schools in Minnesota, received similar threats. Many, however, were on alert.

"NDSU is requiring all employees and students to leave campus by 10:15 a.m.," the initial alert from campus police read. "This includes residence hall students, who, if necessary, should walk to locations off campus."

The alert added that the evacuation also covered the school's downtown buildings and agricultural facilities. NDSU President Dean Bresciani said about 20,000 people, 14,000 of them students and the rest employees, were covered by the evacuation.

The alert gave no details about the bomb threat, adding that more information would be released later.

This is the third bomb threat in eastern North Dakota this week. One closed access to Fargo's Hector International Airport in Fargo, and the other was reported at the Grand Forks airport.

At Minnesota's largest college campus, the University of Minnesota in Minneapolis, there have been no threats, said spokesman Chuck Tombarge. "There is obviously a heightened level of awareness," Tombarge said, and key people, including the campus chief of police, are monitoring the situation.

Across the Red River from Fargo, Minnesota State University-Moorhead officials said they are monitoring the situation closely, but they have not canceled classes. "We have not received any threats," said the director of marketing and communications at MSU-Moorhead David Wahlberg.

NDSU junior Ian Godfrey was in the student union when he received the emergency alert on his cell phone.

Godfrey said everyone was told to "shut everything down, turn off the lights, turn off the TVs" and leave as quickly as possible.

"People were very orderly," said Godfrey, a political science major from Grand Rapids (Minn.) High School. He said university staff members were urging "everyone to stay calm."

"There were some traffic issues getting off of campus," he said, and that prompted the school in a second alert to encourage students and staff to "walk, if necessary."

Senior Jon Zimmerman, of Hopkins, Minn., was working at the University Bookstore in the union when he learned of the threat. "I had to help evacuate the bookstore as well as that wing of the union," Zimmerman said. "Everyone was very orderly and very quick about leaving as fast and as safely as possible."

Psychology major Jordann Brandner, of Bismarck, N.D., said she was just wrapping up a class when the alert came.

"Everyone seemed really stunned, and there was a lot of confusion," said Brandner, hunkered down with five other students at her apartment on the edge of campus. "People were looking at their phones and wandering around a bit."

Also Friday morning, a bomb threat phoned in to the University of Texas at Austin sent thousands of people streaming off campus as administrators warned students and faculty to "get as far away as possible."

University of Texas spokeswoman Rhonda Weldon said the university received a call about 8:35 a.m. from a man with a Middle Eastern accent claiming to be with al-Qaida. The man said he had placed bombs all over the campus that would go off in 90 minutes.

All buildings were evacuated at 9:50 a.m. as a precaution, Weldon said.

Most students appeared to be leaving campus in an orderly and calm manner. Police blocked off roads to the 50,000-student campus as lines and lines of cars sat in gridlock trying to get out.

Ashley Moran, a freshman from Houston, said she was waiting to get into class when word quickly began spreading among students to leave immediately. She described the evacuation as "orderly but tense."

"It makes me really nervous I just know we're supposed to get out," she said.

Star Tribune staff writers Alejandra Matos and Jenna Ross, and the Associated Press contributed to this report.

Paul Walsh • 612-673-4482