Rat sightings have closed down six classroom trailers at a Brooklyn elementary school, with a teachers union official saying she spotted numerous rodents nosing around the temporary classrooms.

Four pre-kindergarten classes, a kindergarten class and a special-education class usually meet in the trailers at P.S. 272. The students have temporarily moved to the main building.

City schools spokeswoman Melody Meyer says the classrooms were closed Wednesday, after a teacher reported seeing a single rat. But the head of the school's teachers union chapter, Janet Zysberg, says she counted a dozen rodents in 10 minutes.

The school has called in exterminators, and the trailers are expected to reopen next week.

The city Health Department recently dispatched inspectors with hand-held computers to boost efforts to combat rat infestations.