Customers and workers at shops along Ajo near Mission thought animals might have been hurt.
It was natural for them to feel this way. After all, it was a 12' X 8' horse trailer they saw crash into a light pole, one designed to transport two horses at a time.
Suddenly, they saw heads popping out of the trailer, and they weren't horses heads.
"They started running out of the trailer," said Brenda Collins, who was working at a dog grooming shop. "They wanted to come in. We held the door and locked the doors, and they were just running everywhere."
Agents from US Customs and Border Protection say there were a total of 42 illegal immigrants inside the trailer. Witnesses say there may have been as many as 60.
In any event, those who could run did, and the border patrol believes it caught all of them.
There were also 12 injured inside the trailer who couldn't run. They were hospitalized, their injuries, non life-threatening, according to border patrol spokespersons.
Agents say they spotted a suspicious looking pickup and trailer near Ryan Air Field shortly after 8am Wednesday. They tried to pull over the pickup, but the driver sped up instead.
Agents say they backed off, out of safety concerns during rush hour. The driver of the pickup lost control, crashing the trailer into a light pole, knocking it down. It fell into the bed of another pickup.
The driver then got out, unhitched the trailer and drove away.
"They not only endangered the people in the trailer, they endangered the people in the stores," said Theresa Troutman, who was in traffic at the time.
Troutman adds that people were likely stacked on top of one another inside the horse trailer.
"There's no way they could all just sit on the floor," she says.
Long after the crash, area hospitals will feel the impact as they absorb the costs of treating the injured.
Illegal immigrants are causing a monetary catastrophe in America's health care system.
From July to December 2005, a six-month period, University Medical Center in Tucson treated 681 foreign nationals at a cost of $6.9 million dollars, according to a study by the University of Texas at El Paso.
Hospitals in Pima County absorbed $76 million for treating illegal immigrants in the year 2000.
Most of the time they simply walk out of the hospital once they're treated and released. The Border Patrol says agents will be stationed at hospitals looking out for the victims of Wednesday's accident, once they're released.
The Border Patrol says one of the illegal immigrants captured is being held on an arrest warrant out of California for forcible sex with a minor.