LONDON – High alert looks something like this.

Curtis Institute president Roberto Diaz was having a perfectly civilized interview on BBC Radio 3's live-on-the-air show "In Tune" around 6 p.m. Thursday,  London time, when a warning came through one of the intercoms in the control room: A "suspect package" had been spotted at a nearby Caffe Nero, a popular coffee chain here, and evacuation may have to happen.

Minutes later – just before Diaz (also a violist) was due to play a Mozart duo with graduating violinist Kevin Lin – the announcement came through that the evacuation was for real.

"Can I have your attention please. Due a security incident…can we request that all members of staff leave the  building…," intoned the anonymous voice over the loudspeaker.

The interview, which publicized the Curtis Symphony Orchestra's upcoming European-tour performance Friday in Cadogan Hall, was wrapped up quickly but gracefully, and a recording was put on where Mozart would've been – "Hopefully something long, like a Bruckner symphony" was one wisecrack heard in the elevator.

Diaz, Lin, and some fellow Curtis musicians who had played a movement from Mozart's Flute Quartet in G just before the evacuation joined throngs of others out on the street. The incident was handled with good humor by the musicians.

Though raised in Atlanta, Diaz was born in Chile, and thus had a philosophical point of reference: "Probably in Chile we experienced incidents like this and you just roll with it. You act quickly, do what you're told, and get to safety. Most of the time these things turn out to be nothing, thank goodness. We're all safe and out of the way."

Fire trucks arrived and police sirens were heard, but within a half hour they were gone.

Had it not been preempted by the evacuation, Lin's chamber music debut on BBC 3 would have occurred on a rather special day in his life: Today it was announced that he'd landed the prestigious co-leader position for the London Philharmonic Orchestra.

During one of his tryout concerts with the orchestra, "I had one 15-second solo in the Vaughan Williams Symphony No. 9 that was BBC broadcast," he said. But he knows there will be many more opportunities to be heard over the airwaves.