President Trump on Monday defended the use of tear gas by U.S. agents against Central American migrants at the San Ysidro border crossing, saying that authorities “had to use” the chemical agent in Sunday’s chaos and dismissing reports that children were among those affected.

“They’re not, as you know. They’re not,” Trump told reporters outside the White House when asked whether he was comfortable with the tear-gassing of children at the border. “They had to use [it] because they were being rushed by some very tough people. And they used tear gas. Here’s the bottom line: Nobody’s coming into our country unless they come in legally.”

U.S. authorities Sunday closed the Southern California border crossing, the busiest port of entry along the U.S.-Mexico border, as hundreds of migrants rushed the fencing hoping to cross onto U.S. soil from Tijuana. Images from the scene showed women and children among the dozens of migrants fleeing the tear gas, which was fired by U.S. Customs and Border Protection agents.

Homeland Security Secretary Kirstjen Nielsen said in a statement that some of the migrants had “sought to harm CBP personnel by throwing projectiles at them.”

The decision to use tear gas sparked broad condemnation from Democrats and others.

“This is wrong,” former secretary of state Hillary Clinton, Trump’s 2016 presidential campaign opponent, said in a Monday afternoon tweet responding to a story about migrants fleeing from tear gas during the unrest.

Tom Perez, chairman of the Democratic National Committee, also denounced the action, tweeting Sunday night: “Shooting tear gas at children is not who we are as Americans.”

In Monday’s brief exchange with reporters, Trump said that Mexico, which has deployed bus loads of police around the migrant encampment, “wants to see if they can get it straightened out.”

“We’ve during certain times, as you know, closed the border. They’re not coming into the United States,” Trump said.

Sarah Kinosian in Tijuana, Mexico, and Joshua Partlow in Mexico City contributed to this report.