HOUSTON » Federal agents have raided more than a dozen bus companies in Houston they say dispersed illegal immigrants across the U.S. in wide-reaching smuggling networks.

Immigration and Customs Enforcement officials say 14 businesses were targeted this week, including one that used armed guards and pit bulls to hold immigrants in a stash house.

ICE Assistant Secretary John Morton says 22 people were charged with conspiracy to transport illegal immigrants, which carries a maximum 10-year prison sentence and $250,000 in fines. ICE agents also detained 81 suspected illegal immigrants.

Morton says the companies charge up to $650 for a one-way ticket and pay $200 to $300 to smugglers per immigrant. Morton says Houston has become a hub and the raids followed a three-month investigation.