Why did border agents fire tear gas at migrants trying to come to the US?

A group of migrants rushed the wall between Tijuana and San Diego on Sunday. The Border Patrol responded with tear gas. Forty-two people who managed to make it across were arrested on the U.S side. The border was closed for more than five hours at San Ysidro, which is the busiest port of entry to the U.S that isn’t an airport. We look at what happened, and discuss the legal questions around it.

Maria Lila Meza Castro (C), a 39-year-old migrant woman from Honduras, part of a caravan of thousands from Central America trying to reach the United States, runs away from tear gas with her five-year-old twin daughters Saira Nalleli Mejia Meza (L) and Cheili Nalleli Mejia Meza (R) in front of the border wall between the U.S. and Mexico, in Tijuana, Mexico November 25, 2018.