A police officer was forced to stand guard with a shotgun as a tour guide waded through crocodile-infested waters after people became trapped in a flooded car.

The two people were attempting to cross the notorious Cahills Crossing in the Northern Territory in a red Mitsubishi Magna when they became trapped.

The deadly waterway on the East Alligator River on the eastern edge of Kakadu National Park is arguably the most dangerous in the country with a man dying there last year and a recent survey finding more than 120 crocodiles within six kilometres of the crossing.

The two people were trapped until a tour boat from Guluyambi arrived to pull the driver and passenger to safety.

An officer is pictured standing on the back of a ute wielding a shotgun, on the look out for crocodiles during dangerous rescue operation at Cahills Crossing in the Northern Territory

Police officers from Gunbalanya arrived about 40 minutes later to tow the vehicle,' the NT News reported.

Spectacular images, captured by tourists on a nearby boat, show an officer wielding a shotgun as men wade through the water to tow the car.

Gunbalanya officer in charge Remote Sergeant Scott Lewis was pictured standing on the tray of a ute, gun in hand, watching for crocodiles.

The dangerous rescue unfolded about 3pm on May 21 and was only brought to the attention of local rescue crews thanks to the tourist boat.

Jabiru local Reijo Keitaanpaa, who watched the rescue operation, said it was entirely luck the tourist boat passed when it did.

A tour guide boat is seen pulling two people from the red Magna at Cahills Crossing

Cahill's Crossing (pictured) in the Northern Territory is notorious for crocodile-infested waters, with more than one person losing their life to the animal at the crossing in recent years

'I'm pretty sure they were relieved the tour boat turned up as any attempt to walk out through the water would have washed them away,' he told the NT News.

While the rescue operation was dangerous, Mr Keitaanpaa said the man leading the charge was experienced.

'He was in and out pretty quickly and it looked like it hadn't been the first time he'd done it because it was all done very quickly,' he said.

Guluyambi Cultural Cruise tour's Nik Wheatley, responsible for the rescue operation, said the incident was not uncommon.

'This happens too often, we're talking dozens of times a year,' he said.

Mr Wheatley said the red Magna was the third car since April to become stuck.

Cahill's Crossing is on indigenous land to the east of the national park and is notoriously difficult to cross

Seven people were rescued by park rangers after their 4X4 broke down in the middle of the river in December 2016.

The group were forced to clamber on to the vehicle's roof and shout for help until finally a passer-by heard them and called the emergency services.

At least 120 saltwater crocodiles call the six kilometre area south of Cahill's Crossing, in Kakadu National Park, home

Cahill's Crossing is on indigenous land to the east of the national park and is notoriously difficult to cross.

Seven people were rescued from the exact same spot in December 2016 after their vehicle broke down on Cahills Crossing

The crossing is littered with signs instructing people not to wade through it on foot.

People, often tourists, regularly get stuck at the flooded crossing after underestimating the water's depth.

The number of crocodiles at Cahill's Crossing has grown so high that drivers are now warned to give way to crocodiles that are walking over the ford.

Crocodile numbers in the Northern Territory have skyrocketed to an estimated 100,000 since crocodile hunting was banned in 1971.