A woman pictured fleeing with her kids from tear gas used at the US-Mexico border over the weekend said she did not think US Customs and Border Protection agents would use the gas on children.

Maria Lila Meza Castro arrived at the border to seek asylum on Sunday alongside other Central American migrants, many of whom were met with tear gas.

Amid outrage over the use of tear gas, President Donald Trump has defended it, saying it was needed to combat "very tough people," and claimed that agents did not use the gas on children.

Tear gas is by nature difficult to target and can easily affect other people nearby.

The CBP commissioner said that the move "prevented a dangerous situation from getting worse" and that no one was seriously hurt in the incident.

A woman pictured fleeing with her kids from tear gas used at the US-Mexico border over the weekend said she never thought US Customs and Border Protection agents would use it on children.

Maria Lila Meza Castro, from Honduras, arrived at the border on Sunday with her five children, who range in age from toddlers to teenagers, to seek asylum. She came alongside hundreds of other Central American migrants who formed part of a caravan that had been traveling to the US.

Migrants were blocked by the Mexican police at a border facility near Tijuana. Some reportedly attempted to get through wire, fences, and metal sheeting, and CBP agents released tear-gas canisters.

"The first thing I did was grab my children," Meza told Reuters in an interview at a migrant shelter in Tijuana. "I was scared, and I thought I was going to die with them because of the gas."

Migrants, including children, flee from tear gas used by US Customs and Border Protection agents at the border. REUTERS/Hannah McKay

About 5,200 people who traveled in the caravan are in the shelter, in makeshift tents in a stadium, according to Reuters.

In a widely circulated image that has sparked outrage over the US's use of the tear gas, Meza is holding the hands of her 5-year-old twin daughters, Saira and Cheili, and running from the gas.

Read more: Backlash erupts after the Trump administration fires tear gas at migrants in clash at the US-Mexico border

"We never thought they were going to fire these bombs where there were children, because there were lots of children," Meza told Reuters.

She said her young son James nearly fainted after a tear-gas canister landed near him.

"It wasn't right," she said. "They know we are human beings, the same as them."

A CBP representative confirmed that agents deployed "crowd-dispersing devices," including pepper-ball launching systems and CS gas canisters — commonly known as tear gas — to deter the migrants.

Meza with two of her children at a migrant shelter in Tijuana, Mexico. REUTERS/Hannah McKay

President Donald Trump has defended the agents' use of the tear gas, saying they were "being rushed by some very tough people."

Trump denied that tear gas was used on children, despite photo and video footage showing children affected by the gas.

According to CNN, when asked by a reporter whether it's OK to use tear gas on children, Trump said: "We didn't. We don't use it on children."

Trump also said it was a "minor form" of tear gas, though the CBP commissioner, Kevin McAleenan, said that the only kind, "standard law-enforcement issue," was used.

Read more: Conservatives are zeroing in on Obama's immigration history to defend Trump, but experts say that's a 'tactic for distraction'

McAleenan told reporters that closing border facilities on Sunday "prevented a dangerous situation from getting worse," according to CNN. The news outlet described him as saying that the decision to use tear gas "was made by agents on the scene using their professional judgment."

The incident will be reviewed in line with protocol, McAleenan said, adding that the agency's initial report said that 69 people were apprehended entering the US and that no one was seriously injured.

Homeland Security Secretary Kirstjen Nielsen has also defended the use of the tear gas, saying the White House had "warned about the danger" facing those traveling to the US.

Mexico's government has called for "a full investigation" into what it described as non-lethal weapons directed toward Mexican territory.