A South Florida elementary school has been evacuated after a pressure cooker was found outside the building.

Video footage from television station helicopters showed teachers, students and staff gathering on a playground outside Hialeah Elementary School on Thursday morning.

The bomb squad has been called to investigate. The pressure cooker was spotted under a tree near the school's kindergarten building.

Police and firefighters have also responded to the school, which is near Miami.

No further details were immediately available.