DALLAS—Police arrested on Monday a group of suspected bank robbers allegedly responsible for at least 20 holdups in North Texas in recent years.

A joint operation involving police from Dallas, Plano, Richardson and Garland assisted the FBI in arresting at least seven suspects, the Dallas Morning News reported in its online edition Monday.

Dubbed the “Scarecrow Bandits” for the loose shirts and floppy hats worn during the robberies, the gunmen usually worked in teams of five or six.

FBI spokesman Mark White said authorities believe the men are responsible for as many as 21 bank robbers since July 2007. He said the arrests were made after officers thwarted yet another robbery attempt earlier in the day.

“It’s still kind of a dynamic situation right now,” White told the newspaper.

Calls to the FBI in Dallas were not immediately returned.