MEXICO CITY (AP) — Mexican immigration agents on Wednesday detained almost all of the Central American migrants on a fourth caravan that recently entered Mexico seeking to reach the United States.

Mexico’s National Immigration Institute said 213 migrants were detained and taken to a processing center. Those found to lack proper documents may face repatriation to their home countries.

The migrants detained on a highway between the Guatemalan border and the southern Mexican city of Tapachula included 186 people from El Salvador, 16 from Guatemala, 10 Honduras and one Nicaraguan.

The group set out from El Salvador on Nov. 18 and apparently crossed the river dividing Guatemala and Mexico on Tuesday. That is the same route the three larger caravans took after entering Mexico starting Oct. 19.

The caravans find strength in numbers, and Mexican officials have been loath to confront the first caravans, which numbered between 1,500 and 6,000. But agents have detained smaller groups that split off from the larger caravans.

Mexico has offered residency and other types of visas to migrants in the caravans, but most have refused, saying they want to reach the United States.

Also Wednesday, prosecutors in the northern state of Baja California — where the first caravan is now camped out — confirmed that a migrant was run over and killed by an unidentified vehicle on a highway between the border cities of Mexicali and Tijuana.

The state prosecutor’s office said 17-year-old Oscar Baudiel Cruz Alcerro, of Honduras was found dead on the roadside with fractures and a dented skull, with parts from a white car scattered nearby.

Migrants stranded in Mexicali have been walking and hitching rides to join up with the main part of the caravan in Tijuana, about 110 miles (180 kilometers) to the west.

At least one other migrant was killed early in the caravan when he fell off a truck on a highway in the southern state of Chiapas.