Some parts of Australia's Top End are teaming with crocodiles, but throwing a few into a school is going to get you in a lot of trouble.

Northern Territory police are on the search for four men who were captured on CCTV footage breaking a window of a school's administration off, then let off three saltwater crocodiles into the area.

The incident happened early on Sunday morning, with police particularly concerned about the condition of the crocodiles dumped by the vandals.

Image: nt police Image: NT POLICE

"The ranger that turned up was very concerned for them — they had their mouths taped up," Senior Constable David Gregory told ABC News. "They haven't seen water for a long time and are undernourished."

It's believed the reptiles originated from a crocodile farm, but the state of the animals will likely result in them being put down.

"We'll determine what farm they’re from and we'll try to take them back to that farm but looking at their condition it’s likely they'll have to be destroyed," ranger Luke McLaren told ABC Radio according to AAP.

Saltwater crocodiles are a protected species in the Northern Territory and taking or interfering with the animals is a criminal offence. Fines are A$77,000 or five years in jail. Plus, let's face it, it's a pretty awful thing to do.