Shocking surveillance footage taken at the Mexican border shows heavily armed men escorting migrants into US territory.

Government footage obtained by Fox News showed several men armed with rifles conducting the covert operation near the town of Lukeville, Arizona at 10pm on Saturday night.

In the black and white video, a Guatemalan woman and her 8-year-old child can be seen being escorted across the border by the armed smugglers.

The Guetamalan woman and her eight-year-old child were filmed being taken across the US-Mexico border

Four or five men can be made out wearing tactical gear and masks and carrying AK-47s as they take the migrants under a vehicle barrier.

After the two successfully cross the border, the men can be seen turning back and leaving.

But soon afterwards, the woman and child turned themselves into border agents, who responded to the incursion.

As many as 12 agents were said to have responded after camera operators noticed the operation taking place on Saturday. The mother and son remain in government custody.

Border patrol officials said operations of this kind are not a regular occurrence but they expressed concern that it may soon happen more often.

Border Force officials responded after surveillance cameras spotted the incident unfolding on Saturday night

'This is highly unusual and highly concerning to the agency,' said a border official who briefed Fox News.

'These armed individuals along the border represent an escalation of tactics. This is not mom and dad and kids deciding to head to the border. This is a no kidding, orchestrated effort to bring individuals to the US. It is not just the numbers. It's who is running this enterprise.'

Border officials said the incident represents how criminal organizations are behind the lucrative surge of Central American immigrants. Guatemalans are paying roughly $7,000 to smugglers for transport from their home to the U.S. border.

The area is almost identical to where last week agents apprehended 399 Guatemalan immigrants who arrived in several buses just 100 yards from the border.