The dead chickens were found by a custodian the morning of Nov. 24 at El Monte Elementary School at 1400 Dina Drive, Concord police Lt. David Hughes said.
Police officers arrived at the school and found the door to a chicken coop on campus had been pried open and the two chickens had been strangled.
The four other chickens were unharmed and running loose in the school, Hughes said.
On Tuesday, a Concord police school resource officer learned information that pointed to three teenage boys, a 14-year-old and two 15-year-olds, as suspects in the crime, Hughes said.
He did not know whether the boys had gone to El Monte before graduating to middle and high school.
The boys were arrested on suspicion of animal cruelty and burglary this morning at home and at their schools, and were later released into the custody of their parents. They are not being identified because they are minors, Hughes said.
Anyone with additional information about the case is asked to call Officer Renee Stevenson, a Concord police school resource officer, at (925) 603-5856. People wishing to remain anonymous can call the Police Department's tip line at (925) 603-5836.