Transcript for Tensions rise in violence at border town of Tijuana

The imamgs of the tar gas used at the u.s./mexico border seen across the country and the world. Thousands of migrants from that caravan have now arrived in Tijuana. Some of them breaking through Mexican security, U.S. Border patrol, then firing tear gas at them. This mother and her children among those caught in the chaos. Tonight, president trump was asked about the tear gas, and here's ABC's chief national correspondent Matt Gutman from Tijuana. Reporter: Tonight, more than 100 migrants deported after those vie lant clashes in tee yab that. Hundreds of Central American migrants first clashed with Mexican police. Then, rushed the border fence. They were met by a wall of tear gas unleashed by heavily-armed U.S. Agents behind those coils of wire. Some of those migrants throwing the canisters right back. Thick smoke sending mothers with children in diapers into a panic. Today, the president denied that agents used tar gas against children. Are you comfortable tear gassing children like what we saw at the border? They're not, as you know, they're not. They had to use, because they were being rushed by some very tough people. Reporter: We met 16-year-old Henry in those bandages. One of the things he says is that he's not going to stop, he wants to still get into the United States, and he's not going to quit now just because he was wounded. The clashes forced authorities to close this port of entry, one of the busiest on the planet, for nearly seven hours. Thousands of people, most there legally, stranded at the border. All right, Matt Gutman with us live tonight, and Matt, the department of defense just announcing that they're moving more troops to California, to the border there to offer support? Reporter: That's right. 300 additional troops to California, bringing the total there to 1,800. Now, there is a concern of a prolonged standoff here, the migrant caravan is expected to swell to over 9,000, and it could take months, David, just to process all those asylum requests. All right, Matt Gutman, thank you.

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