One person from the barge has been taken to hospital and two others are missing at the moment.
It's not known yet whether anyone was inside the plant.
Enormous plumes of black smoke have could be seen for miles.
Officials don't yet know what caused the explosion but say there's no sign it was anything except an accident.
And there's no serious threat of the fire spreading to Manhattan itself, in New York City.
People say they felt the ground shake ten miles away when the explosion happened.