Agents with the US Immigration and Customs Enforcement agency arrested 39 illegal immigrants last week in the Boston area who have criminal records, including 20 people with felony convictions for charges including sexual assault and assaulting a police officer, authorities said.

The suspects, who range in age from 18 to 52, were arrested for being in the US illegally but were targeted because of their criminal histories, and most of them are now in federal custody pending deportation proceedings, ICE said in a statement.