Hundreds of residents have taken to the streets of a Mexican border town, in protest at the arrival of thousands of migrants trying to get to the US.
They were urging the migrants to leave Tijuana, to the south of California.
The migrants are part of a large caravan of Central Americans who have been travelling though Mexico to the US, where they want to claim asylum.
In response to their arrival, the US and Mexico installed heavier security at the border crossing.
Tijuana Mayor Juan Manuel Gastelum said on Friday he expected the number of migrants arriving in the city in the coming weeks to reach 10,000, warning the city was not prepared to handle the "avalanche".
The city's shelters are already struggling to cope, and authorities have asked for government assistance.
Mr Gastelum's words were seized on by US President Donald Trump on Sunday.
"The Mayor of Tijuana, Mexico, just stated that 'the City is ill-prepared to handle this many migrants, the backlog could last 6 months,'" he tweeted.
"Likewise, the U.S. is ill-prepared for this invasion, and will not stand for it. They are causing crime and big problems in Mexico. Go home!"
The anti-migrant feeling could also be seen on the streets of Tijuana.
"They are invaders! They are armed! Get out of the country," protesters shouted, according to Reuters news agency.
Esther Monroy, 58, told AFP news agency she feared the numbers of migrants gathering in the city would lead to the US closing the border crossing,
"Most of us in this depend on business from people coming and going across the border," she said.
"If they close it, it will be [the migrants'] fault."
"If the government can't control all this, organised crime and drug cartels will," America Villa added. "We don't care who does it, but they have to take responsibility for these people."
However, not everyone was protesting against the migrants. A smaller demonstration was also held in support of the new arrivals, who say they are fleeing persecution, poverty and violence in their home countries of Honduras, Guatemala and El Salvador.
And there was even understanding from the migrants themselves.
"They have the right to protest because they don't like that we're here but in spite of everything, they [Mexicans] are good people," Karina Rosales, a migrant from Honduras, told Reuters.
"They are the same as us. But we're only passing through. We won't stay here."