Immigration authorities have rescued more than three dozen immigrants who were locked inside a sweltering boarded-up bedroom in a Southern California house.

Immigration and Customs Enforcement officials said Wednesday some of the 37 immigrants from six Latin American countries had been held for weeks in the 10-by-10-foot room in Riverside and had gone several days without food.

The immigrants, mostly men, had been stripped of their shoes and were found lying on the floor. Three children under 3 years old were also found inside the room, said Debra Parker, assistant special agent in charge for ICE Homeland Security Investigations in Riverside.

Authorities say they began searching for the house after a caller reported smugglers had threatened to kill his relative when the family could not pay for his release. After scouring the area for two days, including with an infrared-equipped helicopter, officials searched the home Tuesday afternoon.

Smugglers often hold illegal immigrants in so-called drop houses for days or weeks while collecting payment for bringing them into the country.