Transcript for Border Patrol claims that some migrants have illegally entered the US

Closer to home tonight the showdown on the U.S. Border. The caravan of men, women and children from Central America arriving at a U.S. Border post. The question tonight, what happens next. Matt Gutman on the border tonight. Reporter: Tonight, that standoff at the Mexican border intensifying. Some scaling to the top of this border fence. Customs and border patrol claiming some migrants have now illegally entered the U.S. They had made the 2,000 mile, month long trek from southern Mexico on buses, train and on foot. Mari Martinez said her family of nine, including a daughter in a wheelchair, have been pursued by ms-13. Reporter: She said if I stay in my country I'll be killed. President trump repeatedly warning the migrants should not be allowed into the united States. Are you watching that mess that's going on right now with the caravan coming up? Reporter: But the migrants here say they won't give up. David, for any asylum seeker the longest part of the journey by far is getting their asylum granted once in the us. It can take years and it hinges upon something called a credible threat interview. Basically these migrants have to prove they face persecution if they're sent back home. A majority of them are sent home. David. Matt Gutman on the border. There are developments in the serial killer investigation

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