ST. LOUIS (AP) – Animal humane groups say more than 400 dogs including some that were about to deliver puppies have been rescued in the largest coordinated raids on dogfighting in U.S. history.

Federal, state and local law enforcement agencies conducted the raids Wednesday and Thursday and made arrests in Missouri, Illinois, Iowa, Texas and Oklahoma following a more than year-long investigation.

Authorities have indicted at least 26 men – including a registered nurse, Little League coach and teacher – on federal charges. They say the alleged criminal enterprises weren’t part of an organized network, though some suspects were acquainted.

Humane groups says most of the dogs American Pit Bull Terriers.