HEBBRONVILLE, TEX., JULY 8 -- Border Patrol agents freed 19 illegal aliens locked in a sweltering railroad trailer today, preventing a tragedy similar to the one that left 18 aliens dead in west Texas last week, officials said.

The rescued men had stripped to their shorts in the 120-degree heat and lapsed into semiconsciousness, but none required medical assistance, U.S. Immigration and Naturalization Service spokesman Mario Ortiz said.

"In the wake of what happened in Sierra Blanca, this is pretty serious stuff," Ortiz said from his Dallas office.

Meanwhile, agents in San Clemente, Calif., found 88 illegal aliens, including four women and a child, inside a locked tractor-trailer rig. Some required medical treatment but none was hospitalized. On Tuesday, 53 aliens were discovered hiding in a truck in San Diego.

In Hebbronville, as in the July 2 incident outside El Paso, the men had been locked in the trailer by a smuggler just before the train left Laredo en route to Corpus Christi, Ortiz said.

"It's the same thing," Ortiz said. "They were latched in and couldn't get out. It was 95 degrees outside, and easily 120 degrees inside by the time they were found at 11 a.m. If they had been in there much longer, they would have been dead."

"The aliens, all of whom are in their late teens and early 20s, were semiconscious due to extreme heat and dehydration," Border Patrol agent J.J. Fulgham said in Laredo. The men had been in the Texas-Mexican Railroad trailer about four hours, he said.

During a routine inspection stop in Hebbronville, 60 miles east of Laredo, Border Patrol officers found the group inside the trailer, which attaches to tractor-trailer trucks and was perched on a flatbed railroad car.

"The men, who we believe to be Mexicans who came across the border from Nuevo Laredo, were taken to the Border Patrol station in Laredo," Ortiz said. "They'll be deported, but not before an intensive investigation. This is another smuggling case. But luckily, we were able to save them."

Ortiz said officers arrested five others aliens who apparently jumped off the train as it approached Hebbronville.

"We don't know if they're connected to the 19 who were locked in. We're investigating that," he said.

The smuggler in the Laredo case had tossed in some tools before latching the trailer door shut, but the people inside could never have chiseled through the metal walls, Ortiz said.

In the El Paso incident, the smuggler provided railroad spikes for the aliens to chip through the airtight car's heavy wooden floor. Only one of the men aboard, however, lived long enough to poke through for air.

"It is likely this group would either have died or have been in critical condition had our agents not found them," said Stephen Martin, southern regional commissioner for the U.S. Immigration and Naturalization Service.

However, Fulgham said that agents were finding fewer aliens on routine inspection of freight trains leaving Laredo for San Antonio and Corpus Christi since a new immigration law went into effect earlier this year.

Before the new law, Border Patrol agents daily would find as many as 200 illegal aliens aboard trains headed for the interior of Texas, Fulgham said, adding that the number now is closer to 50.

California weigh-station officials in San Clemente became suspicious when they noticed liquid, believed to be sweat and urine, dripping from the bottom of the trailer, said Gene Smithburg, assistant chief patrol officer for the U.S. Border Patrol in San Diego.

"The inspectors felt the sides of the truck and it felt unusually warm," Smithburg said. "They called our agents over and they pounded on the sides. People inside began hollering and screaming."

Border Patrol agents from the nearby San Clemente checkpoint on Interstate 5 used bolt-cutters to enter the rear of the tractor-trailer, which was stopped at truck inspection scales about 12:45 p.m. PDT, he said.

"The people inside were in pretty bad shape," Smithburg said. "Several of them had to be treated on the spot for heat exhaustion, but nobody required hospitalization."