Officials reopened the pedestrian border crossing around 3:45 p.m. Sunday, then reopened vehicle lanes around 5 p.m.
Some 7,400 of the migrants are now gathered in the Mexican border state of Baja California, in the cities of Tijuana and Mexicali, and tensions have risen in recent days amid a series of daily protests. You have a lot of people who grab children.
"I do say, why are they there?"
Her young son James almost fainted when a canister landed near him.
So far, around 2,400 members of the migrant caravan have reached the U.S. -Mexico border, and a thousand more are expected this week.
"But now it seems that they want to kill us, and we got very scared", said Jimenez.
For weeks before the 6 November congressional elections, Mr Trump raised the alarm about the migrant caravans and ordered some 5,800 United States troops to the border to support border patrol agents.
The migrants, mostly from Honduras, are part of a "caravan" loudly condemned by President Donald Trump.
A Central American migrant sits on top of the border structure separating Mexico, left, and the United States, right, as U.S. Border Patrol agents look on, right, Wednesday, Nov. 14, 2018, seen from Tijuana, Mexico.
Police use tear gas on migrants at U.S. border
President Trump essentially gave the green light for retaliation a few weeks ago as the migrant caravan made its way north. Videos posted on Twitter showed large numbers of migrants dashing across a shallow concrete waterway towards the border.
Border Protection agents launched pepper spray balls in addition to tear gas in what officials said were on-the-spot decisions made by agents.
The San Ysidro Port of Entry - the busiest land border crossing in the western hemisphere, according to the federal government - was shut down for around five hours Sunday.
This agreement would change long-standing USA policy and would place a strong barrier in the path of Central American migrants attempting to reach the United States "fleeing violence and harm", says David Leopold, past president of the American Immigration Layers Association, based in Washington, D.C. "Many Tijuanans work, study, and visit the United States in healthy peace".
The Rev. James Martin, a Jesuit priest and author, decried the myths that have led Americans to turn their backs on migrants who have come to the border seeking asylum.
"The alarm went off and they began throwing tear gas at us".
The mayor told UPI the city has no plans to evict the migrants from the camp, but said that was ultimately up to federal authorities. Under US and worldwide law, an unauthorized crossing is not grounds to block someone from claiming asylum; neither does it change limits on the appropriate use of force.
Also on Monday, his Department of Homeland Security Secretary Kirstjen Nielsen said in a statement that the male members of the caravan were using the women and children in their favor.
"But it's a term that's used because many people, it's a very violent awful thing, but they feel they have an advantage when they're with a young child. I think there is no chance", he said.
The chaos comes as USA and Mexican officials wrangle over the issue of migration and discuss how to deal with asylum-seekers waiting in Mexico.