A car bomb ripped through a campus parking lot at a university in northern Spain on Thursday,injuring 17 people in an attack blamed on the Basque separatist group ETA.
Staff at the University of Navarra in the city of Pamplona described how the initial blast at around 1000 GMT set off a series of smaller explosions as several other cars erupted in flames.
"There were other small explosions after the fire set off the fuel tanks in the parked cars nearby," professor Bernardino Leon told the Antena 3 TV channel.
Spanish Interior Minister Alfredo Perez Rubalcaba told a press conference it had been a lucky escape as nobody had been close to the bomb when it went off.
"A major tragedy could have occurred today at the University of Navarra," he told journalists, adding, "We have had some luck in the misfortune."
He said a man claiming to represent ETA had put in a warning call to the regional DYA traffic department.
Calls to DYA have often been used by ETA to warn of imminent explosions in the Basque country.
The man said a "white Peugeot" was going to explode at a nearby university without specifying which one, according to Rubalcaba.
A second professor at the university, Ramon Salaverria, described the intensity of the blast.
"I felt the whole building shake and I thought it was an earthquake. And then I saw a column of smoke about 30 to 40 metres high," he said, according to the website of the 20 Minutos newspaper.
Some 400 people were evacuated from nearby buildings after the explosion, although the rest of the campus continued to function as normal, said the university's director of communication Jesus Diaz.
The blast comes two days after the arrest of four suspected members of armed Basque separatist group ETA -- three of whom were picked up in Navarra.
Spain's interior ministry said the group "were ready to carry an attack, probably in Navarra."
The university said they had received no warning before the blast, but Among other demands, radical Basque separatists want to include the separate autonomous region of Navarra in Basque Country.
Founded in 1952, the University of Navarra is a private Catholic university, linked to the Roman Catholic organisation Opus Dei. This attack is the sixth of its kind at the university -- the last one being in May 2002, when a bomb injured three people.
ETA is considered responsible for 824 deaths in its 40-year-long violent campaign for an independent nation in northern Spain and parts of southwestern France. It is classified as a terrorist organisation by the European Union and the United States.
The group resumed its campaign of attacks after breaking its last ceasefire in June 2007, and has been responsible for five deaths, including three Spanish security officers, one soldier and a former Basque Socialist elected official.
The Basque Country already enjoys considerable autonomy and polls show most Basques do not want to split from Spain but a vocal minority is pushing for an independent Basque homeland.
Last month the country's Supreme Court banned two Basque independence parties linked to Batasuna, ETA's outlawed political wing.
Spain's Constitutional Court meanwhile declared illegal the Basque regional government's plan to hold a referendum on self-determination for the wealthy region.
