BOSTON (CBS) – A Sterling animal shelter is now offering up to $2,000 for the safe return of two stolen puppies.

Four people have been arrested in connection with the robbery of nine puppies. Seven of the dogs have been found as of this past weekend.

READ MORE: Spencer Crash Leaves Two 17-Year-Old Boys With Serious Injuries

Last Friday, a dead black and white puppy was found in Worcester, but officials are still investigating whether the dog is one of the missing ones.

READ MORE: Northeastern Requiring All Faculty, Staff To Be Vaccinated For Fall Semester

“As more time goes by the more dire the situation becomes,” said Leigh Grady, Executive Director of Animal Shelter Inc. located in Sterling, MA.

MORE NEWS: Jury Selection Begins In Trial Of Thomas Latanowich, Charged With Killing Yarmouth Police Sgt. Sean Gannon

Anyone with information is urged to call the Sterling Police Department at 978-422-7331 or Animal Shelter, Inc. of Sterling at 978-422-8585.