KRQE-TV reports (http://bit.ly/11ZdIEQ) that the 24-inch-long tortoise with severe wounds was spotted by the group last week. Police say officers found a 14-inch knife and a hammer close to where the injured turtle was discovered.
The tortoise later died.
Police say investigators don't believe the juveniles had anything to do with the attack.
Investigators took the knife and hammer to test for DNA and fingerprints.
No arrests have been made.
Information from: KRQE-TV, http://www.krqe.com