Stamford police and immigration officials have arrested seven illegal aliens in a nationwide crackdown of wanted immigrants.

The seven arrests come as part of "Operation Return to Sender," which targets illegal immigrants who have been previously deported or convicted of crimes. Cops say the lead bust is a twice-deported Colombian national convicted for narcotics trafficking and heroin.

Officials say 150 immigrants have already been rounded up in New England. Police say they are still identifying aliens that fit the purpose of the operation.