President Donald Trump on Thursday defended his use of the word "animals" to describe some undocumented immigrants, explaining that he was referring specifically to members of the brutal MS-13 gang.

"We have laws that are laughed at on immigration," Trump told reporters at the White House. "So when the MS-13 comes in, when the other gang members come into our country, I refer to them as animals and guess what? I always will."

Trump touched off the controversy on Wednesday afternoon when responding to a comment by Sheriff Margaret Mims of Fresno County, Calif., about the obstacles she faces in telling the Immigration and Customs Enforcement agency about known gang members.

"We have people coming into the country, trying to come in, we're stopping a lot of them, but we're taking people out of country, you wouldn’t believe how bad these people are," Trump said during the White House meeting with officials from California to discuss that state's sanctuary policies. "These aren't people, these are animals."

After his Wednesday remarks, Trump was rebuked by Democrats and advocates for immigrants, who said he wasn't making a distinction between hardened gang-bangers and people whose only crime is being in the country illegally.

"When all of our great-great-grandparents came to America they weren't 'animals,' and these people aren't either," Senate Minority Leader Chuck Schumer, D-N.Y., wrote on Twitter.

Trump's press secretary, Sarah Sanders, addressed the issue earlier Thursday in a briefing for reporters.

"If the media and liberals want to defend MS-13, they're more than welcome to," she said. "Frankly, I don't think the term that the president used was strong enough."

Trump has used the term to describe MS-13 members many times in the past, including at a rally in Moon Township, Pa., before a special House election, during the Conservative Political Action Conference in Washington's Maryland suburbs and at a school-safety meeting at the White House after the Parkland, Fla., school shooting.