Mexico will deport almost 500 migrants who attempted to storm the US border, according to its interior ministry.
The group were rounded up after trying to cross the border “violently” and “illegally” on Sunday, the ministry said in a statement.
Video footage shows dozens of people – including women and children – running towards the fence that separates the two countries near the city of Tijuana.
They were repelled by tear gas used by US border officers.
Mexico’s interior ministry said all those who were identified as having tried to cross would be deported immediately.
It added that, “far from helping their objectives”, the migrants’ actions had violated the legal migration framework and could have led to a “serious incident”.
Tensions have been high in Tijuana since the arrival of thousands of migrants earlier this month.
The migrants are in Tijuana after travelling more than 4,000km (2,500 miles) from Central America.
They say they are fleeing persecution, poverty and violence in their home countries of Honduras, Guatemala and El Salvador.
However, they now face a long wait to see if their asylum applications will be accepted by the US, with President Donald Trump vowing to keep each migrant on the Mexican side of the border until courts have decided their case. This could take months.
Amid growing desperation on Sunday, a group of about 500 migrants – who had been taking part in a peaceful protest demanding to be allowed to cross – made a run for the border.
According to news agency AFP, a number managed to climb over a first fence. It was as they tried to cross a second, spike-topped wall that officials on the US side began throwing tear gas.
An AFP journalist saw the migrants – including mothers and children – trying to protect themselves from the gas, with some crying out that they only wanted to find a work and a better life in the US.
Honduran migrant Ana Zuniga, 23, tried to cross with her three-year-old. She told AP: “We ran but when you run the smoke smothers you more.”
As a result of Sundays action, the US has also closed the border crossing near the Mexican border city of Tijuana to vehicles and pedestrians.
Mr Trump threatened to close the entire US-Mexico border earlier this week if it was felt the US was going to “lose control” of the situation.
He also said he had given troops at the border the go-ahead to use lethal force if needed.
Mr Trump has deployed about 5,800 troops to the border. He previously described the migrants as an “invasion”.
Migrant caravan: Mexico to deport group which stormed US border