A group of 376 Central Americans have been arrested in southwest Arizona after using short, shallow holes dug under a barrier to cross the border.
The group dug under a steel barrier in seven spots about 16 kilometres east of a border crossing in San Luis and made no effort to elude immigration agents.
The unusually large group was almost entirely from Guatemala. Many were families and they included 176 children.
All were taken to Yuma after entering the country on Monday.
The area became a major corridor for illegal crossings in the mid-2000s, prompting the federal government to weld steel plates to a barrier made of steel bollards that had been designed to stop people in vehicles, not on foot, Border Patrol spokesman Jose Garibay said. In those spots, there is no concrete footing to prevent digging.
The group used multiple holes in an apparent effort to get everyone across the border quickly, Garibay said.
Customs and Border Protection released photos and video of a long line of migrants standing patiently on a desert road's dirt shoulder after they were stopped.
On Wednesday, the Border Patrol arrested a group of 247 people, mostly from Central America, who turned themselves in to agents in a highly remote part of New Mexico, where authorities have found 25 groups of more than 100 people since October.
A group of 115 was found in the same area on Thursday.
Despite a surge in asylum-seeking families from Central America in recent months, border arrests remain low by historical standards.
The Border Patrol made 396,579 arrests on the Mexican border in the 2018 fiscal year, up 30 per cent from a 46-year low during the same period a year earlier but still well below a high of more than 1.6 million in 2000.
