Five people trying to sneak into the United States from Mexico were rescued Tuesday after they were trapped in a small tunnel leading to a storm drain opening, U.S. authorities said.

The five became trapped when the largest among them, a man weighing about 200 pounds (90 kilograms), got stuck trying to exit the tunnel through the storm drain, said James Jacques, a spokesman for U.S. Customs and Border Protection.

Firefighters used jackhammers to widen the opening and free the man, who had become stuck at the hips. They then pulled out the four others who were stuck behind him.

Seven more people who were behind that group managed to crawl back into Mexico through the tunnel, Jacques said.

The five were freed within 90 minutes and none required immediate medical care, fire dispatchers said.

Two other people who had gotten through the tunnel ahead of the larger man were apprehended in a San Diego parking lot just north of the second of two fences that separate the U.S. from Mexico.

Although no one was hurt, Jacques said a tragedy easily could have occurred in the fetid narrow tunnel.

"This to me illustrates how little smugglers care about human life," Jacques said at the scene. "They risked these people's lives and that's unconscionable."

He declined to say if a smuggler was among those captured, saying the case was still under investigation.

Border Patrol agents had noticed the 14 gathering on the Mexican side shortly before 7 a.m. They moved in to apprehend the first two after they emerged on the U.S. side and found the five others trapped.

The tunnel, only about 2 feet (0.6 meters) across, is part of San Diego's storm drainage system, and authorities were investigating how it was breached from the Mexican side. Jacques said it was most likely someone had connected a makeshift tunnel to one of the storm system's tunnels.

Jacques said the group's capture shows it is getting harder to sneak across the border into the United States.

"This is an example of the fact that people are getting more desperate and trying other means," he said.