No criminal charges will be filed against any of the 42 migrants arrested in a clash that ended with US authorities firing teargas into Mexico, the Associated Press has learned.

Rodney Scott, chief of the border patrol’s San Diego sector, has said those arrested for illegal entry included 27 men, with the rest being women and children.

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The incident occurred on Sunday at the border in Tijuana, where thousands of caravan members have been arriving in recent weeks after fleeing poverty and violence in Central America. Most of them plan to seek asylum in the US but may have to wait months because the US government only processes about 100 of those cases a day.

As frustrations began to mount over the long wait, migrants marched to the border Sunday to appeal for the US to speed things up. It turned unruly when four agents were reportedly struck with rocks or projectiles and authorities responded by launching teargas and pepper spray balls to quell the unrest.

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But in the end, none of the 42 people had charges brought against them for illegally entering the country or any other counts.

Customs and Border Protection, the border patrol’s parent agency, referred only two cases to the justice department for prosecution and charges were not filed because the accused had medical problems that prevented them from being held in San Diego’s detention center, according to a US official familiar with the cases who was not authorized to discuss the matter publicly and spoke on condition of anonymity.

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Many others were not referred to the justice department because they were children or parents accompanying children, the official said.

The other adults were not prosecuted because Customs and Border Protection did not have enough information to pursue charges, including the name of the arresting officers, according to the official, who said it was an extremely chaotic scene.

The fate of the 42 immigrants remains unclear. Customs and Border Protection declined to discuss why charges were not filed but said they still may be subject to deportation.﻿