I took the LSAT Feb 2004 and with two minutes left in one of the sections, the fire alarm went off.
The examiner made us finish the last two minutes in the section while the alarm was going off. (No extra time given or anything).
Then we had to wait outside in the cold for fire trucks to come check the building, before being allowed to return and do the last section.
While the fire alarm was distracting, it was kind of nice to get a longer break than we were supposed to be given! Though, maybe I lost momentum a little bit?