At least one person from Latvia is among 24 men who were freed Sept. 11 from their slave-like conditions at a British caravan site, about 70 kilometers northwest of London, police say.

Five persons, including a pregnant woman, were arrested as part of the investigation. Two other suspects are being sought. About 100 officers were involved in a series of arrests at the caravan site in Leighton Buzzard, according to press releases from Bedfordshire Police.

The men who were freed have been provided with medical and welfare care by British authorities.

“The men we found at the site were in a poor state of physical health and the conditions they were living in were shockingly filthy and cramped,” said Det. Chief Inspector Sean O’Neil of the Bedfordshire and Hertfordshire Major Crime Unit. “We believe that some of them had been living and working there in a state of virtual slavery, some for just a few weeks and other for up to 15 years.”

The men range in age from 17 to 57. They were mostly British or Eastern European, police said. Most of them are cooperating with the investigation.

Dubbed “Operation Netwing,” the investigation “centered around intelligence suggesting that a number of people were being held against their will in poor conditions at the site and forced to work for no pay,” according to a police press release. Police were assisted in the investigation by the United Kingdom Human Trafficking Centre.

The arrests were made under the U.K.‘s Slavery and Servitude Act 2010.

“The new legislation has allowed the investigation more scope and takes into account emotional rather than physical harm,” O’Neil said. “I am confident that while the investigation is in its early stages this is a family run ‘business’ and is an organized crime group that has been broken up by the Netwing operation.”