By Corrie MacLaggan
AUSTIN, Texas (Reuters) - Two large U.S. universities were evacuated within minutes of each other after telephoned bomb threats on Friday, including the University of Texas at Austin, where the caller said he was linked to al Qaeda.
The threats came on a day of what appeared to be heightened tension around the country. A third university also reported an "unspecific threat" while a bomb squad was deployed into downtown Kansas City, Missouri, when a man told authorities he had placed a bomb in a parked car.
It was unclear whether any of the threats were linked, and they resulted in nothing more than inconvenience and fraught nerves.
Still, the threats came against a backdrop of TV images this week showing demonstrators in the Middle East attacking U.S. embassies and burning American flags in anger over a film made in the United States that portrays the Prophet Mohammad as a fool and womanizer.
Authorities have not connected the threats at the universities in the United States with the international demonstrations.
The burst of threats began at the University of Texas at Austin, which has about 51,000 students and 24,000 staff and faculty. Officials ordered the buildings cleared after a telephone call from an unidentified man with a Middle Eastern accent who claimed to have placed bombs on campus, spokesman Gary Susswein said.
"He said he was associated with al Qaeda and said the bombs would go off in about 90 minutes," Susswein said.
Authorities evacuated the school's buildings, searched the sprawling public university, and hours later allowed students to return, although classes were cancelled for the day.
Some students said they were frustrated that the university waited so long - more than an hour - between receiving the call and issuing the evacuation alert.
"I don't really understand why it took them so long to just send a text," said Phillip Lemons, 18, a freshman studying electrical engineering.
Addressing concerns about the delay at a press conference, University of Texas President Bill Powers said the university didn't issue the evacuation order immediately because it was evaluating the call. If the threat had been immediate - something set to happen in five minutes, say - then "you just have to pull the switch," he said.
He also said authorities were "extremely confident that the campus is safe."
Even as the University of Texas was evacuating, North Dakota State University issued its own warning about a bomb threat and told everyone to leave its buildings.
North Dakota State, a public university in Fargo with about 14,000 students, was also eventually re-opened after an investigation. Officials did not disclose details of the threat.
A third school, Indiana's Valparaiso University, a Lutheran college located an hour east of Chicago, also issued a security warning on Friday.
"An unspecific threat to campus was made through a graffiti message alluding to dangerous and criminal activity alleged to be carried out during the chapel break period on Friday," said a posting on its website.
(Additional reporting by Taylor Short, Jim Forsyth, Ian Simpson, David Bailey and Mary Slosson; Writing by Paul Thomasch; Editing by Eric Beech)