Tijuana (Mexico), Jan 2; AFP: A group of 150 migrants from Mexico tried crossing over to the US. The US Border Patrol used tear gas and pepper spray to counter them as they threw rocks while trying to get into the country. This led to 25 arrests.
It is the second time since November that border officers have used tear gas during an attempted mass migrant crossing in the San Diego area. At least three volleys of gas were launched onto the Mexican side of the border near Tijuana's beach.
The migrants in the latest case New Year's Eve were among 1,500 who have remained in Tijuana, Mexico, just south of San Diego, California, after a once-5,000-strong caravan of travellers — which raised the ire of President Donald Trump — largely gave up and dispersed.
According to observers, toddler-sized children were being passed across the concertina wire with difficulty. Agents could not assist the children "due to the large number of rocks being thrown at them."
Agents used smoke, pepper spray and tear gas "to address the rock throwers assaulting agents and risking the safety of migrants attempting to cross who were already on the US side," CBP said.
"The rock throwers were located south of the fence, in an elevated position both above the border fence area and the incursion attempt."
Most of the migrants returned to Mexico using a hole under the fence or by climbing over it, CBP said, adding 25 people including two teenage migrants were detained.
There, the border is marked with fencing and a large vertical plate that juts out into the water.
On the other side of it, US border agents were seen mobilising.
As night fell and people on both sides of the frontier prepared to celebrate New Year's Eve, the migrants tried to cross over but at least two smoke bombs were fired and they were ultimately held back.
Those who tried to cross included adult men, women with small children and adolescents.
After that attempt, part of the group stayed near the border and other Central Americans arrived to join them.
When people in this group rushed the border in a second incident, US authorities fired tear gas to disperse them, an AFP photographer observed.
In a statement, US Customs and Border Protection (CBP) said an initial group of 45 migrants turned back towards Mexico, due to the increased presence of Border Patrol agents.
Shortly after, migrants began throwing rocks over the fence at CBP officers.
Agents "used the minimum force necessary," Katie Waldman, a spokeswoman for the Department of Homeland Security, said in a statement.
In late November, also in the Tijuana area, US border officers used tear gas and rubber bullets when about 500 men, women and children scrambled over a rusted metal fence and surged into a concrete riverbed before they encountered a second fence.
Rights groups raised questions over the use of force, in which at least one man was wounded. CBP said 42 people were arrested on the US side.
The migrants in both cases were part of a caravan that left Central America in October and travelled 4,300 kilometers (2,600 miles) to Tijuana in the hope of reaching the US and requesting asylum.
Many were fleeing gang violence and poverty.
They arrived in Tijuana in early November and today about 1,500 still remain.
The rest asked to be transported back home or dispersed to other parts of Mexico.
Trump used the caravan to stir up fear of immigrants as he pressed his drive to build a wall on the border. Many migrants from Tijuana are waiting to apply for asylum to United States. But, there was more backlog even before the caravan arrived and he wait is expected to be many months.
He has also made it harder for people to request asylum at the frontier.
An impasse with legislators over funding for his border wall project is behind a partial shutdown of US government services which is now in its second week.
