A group of 325 Central Americans surrendered to U.S. Customs and Border Patrol agents after entering the country illegally near the port of entry of Lukeville, Arizona Thursday morning.

Border patrol agents from the Ajo Station spotted a possible campfire seen on their surveillance camera. When they arrived at the area to investigate, they found the large group of immigrants who illegally entered the country from Mexico.

CBP said the group was dropped off by buses and trucks on the Mexican side of the border Wednesday night. They crossed together at 8 a.m. to await authorities in U.S. land.

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There were nearly 150 juveniles in the group and more than 30 of them were unaccompanied, CBP said.

The agents patrolling the area used vans and truck to transport the group from the desert terrain and nearly-freezing temperatures to the nearest facility for processing.

Medical staff checked the individuals in the group.

CBP said four people were sent to a hospital after two juveniles and a 5-year-old possibly had chicken pox and a 12-year-old had a skin infection.

This year alone, the Tucson Sector has reported three groups totaling more than 650 people. A group of 375 migrants dug holes under the border wall near Yuma Jan. 14. Another group of over 100 Central Americans jumped the wall near the same area Jan. 21.