When thieves broke into a southern Californian high school music room this week, they cut through the bolts on all the storage lockers and ripped two doors off their frames. But they didn't touch the computer or the projector or even the trumpets.
''It was strictly a tuba raid,'' said Rolph Janssen, an assistant principal at Bell High School.
The school is only the most recent victim in a string of tuba thefts from music departments. In the past few months, dozens of brass sousaphones - smaller tubas used in marching bands - were taken from schools in southern California.
Although the police have not made any arrests, music teachers say the thefts are motivated by the growing popularity of banda, a traditional Mexican music form in which tubas play a dominant role.
Teachers point to the targeted pattern of the burglaries: the expensive brass tubas and sousaphones, which cost $2000 to $7000, are pilfered but electronics, cheaper fibreglass tubas and other brass instruments are usually left behind.