At least one man was wounded.

Mexico's Interior Department said about 500 migrants were involved in the attempt to rush the border, while US authorities put the number at 1,000.

The incident was the most serious flashpoint in a weeks-long crisis that US President Donald Trump used to drum up support in this month's midterm elections.

Irineo Mujica, who has accompanied the migrants for weeks as part of the aid group Pueblo Sin Fronteras, said the aim of Sunday's march toward the US border was to make the migrants' plight more visible to the governments of Mexico and the U.S.

Around 5,200 people who traveled in a caravan across Mexico are packed into the shelter in a stadium in Tijuana, living in makeshift tents. "Many Tijuanans work, study, and visit the United States in healthy peace".

Oddly enough, the American protesters faced off against a protest group on the other side of the border, protesting against the migrant caravan and in favor of Trump's immigration policies.

In an early Monday tweet, Trump added, "Mexico should move the flag waving Migrants, many of whom are stone cold criminals, back to their countries".

Homeland Security Secretary Kirstjen Nielsen said in a statement that USA authorities will continue to have a "robust" presence along the Southwest border and that they will prosecute anyone who damages federal property or violates US sovereignty.

An Associated Press reporter saw USA agents shoot several rounds of tear gas after some migrants attempted to penetrate several points along the border. Democrats and even some lawmakers in Trump's own party have resisted his calls to fund his proposed border wall. Trump has vowed to shut down the southern border with lethal force if necessary, and is calling on Mexico to intervene.

Sunday's incident happened after a group of migrants in the Mexican border city of Tijuana rushed at the border fencing.

The sudden rush overwhelmed Mexican police, who were deployed with large clear shields and full riot gear. Under US and global law, an unauthorized crossing is not grounds to block someone from claiming asylum; neither does it change limits on the appropriate use of force. Video of the scene showed a cloud of tear gas that sent people running and screaming, including families with young children.

Groups like "Free Our Future" began marching in California on Sunday, demanding an end to border control, totally open borders, and for the United States government to abolish the Immigrations and Customs Enforcement agency.

US Customs and Border Protection officers "were struck by projectiles thrown by caravan members" and "perpetrators will be prosecuted", US Homeland Security Secretary Kirstjen Nielsen said on Twitter. A person got hit and lots of kids fainted.

Many have become desperate in recent days after taking stock of the asylum application process, The New York Times reported. "They grab a child because they think they're going to have a certain status by having a child", he said. He said CBP does not have rubber bullets in its inventory on the border.