'They had to use (it) because they were being rushed by some very tough people and they used tear gas and here's the bottom line: nobody's coming into our country unless they come in legally,' Trump told reporters in Mississippi.
US President Donald Trump on Monday defended the use of tear gas on migrants who rushed the border.
"They had to use (it) because they were being rushed by some very tough people and they used tear gas and here's the bottom line: nobody's coming into our country unless they come in legally," Trump told reporters in Mississippi.
"The tear gas is a very minor form of the tear gas itself. It's very safe," he later added.
Trump also claimed, without providing evidence, that some people at the border are "grabbers" who are using unrelated children as a shield to make it safer for themselves and increase their chances of getting into the US.
"They grab a child because they think they'll have a certain status by having a child. You know, you have certain advantages in terms of our crazy laws that frankly Congress should be changing," he said.
US authorities on Monday fired tear gas canister toward migrants in Mexico near the border crossing separating Tijuana city from San Diego, California - when some rushed through border fencing into the United States.
According to report, as migrants were trying to enter the US, several hundred made it over the first barrier but when they neared the second fence, US border agents fired tear gas and rubber bullets at them as helicopters buzzed overhead.
People covered their faces to protect themselves from the acid gas, as mothers clutched their young children and fled back to Mexico for safety.
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.
The migrants have travelled through Mexico in large groups or caravans. There are more than 7,000 at the US border in Tijuana and the city of Mexicali, with more than 800 others still moving toward the border.
Trump has deployed nearly 6,000 troops to the border, on top of more than 2,000 members of the National Guard.
To enter the US legally, migrants must apply for asylum, but the wait for those requests to be processed can last up to a year.