From the Massachusetts State Police (verbatim):
There is a scam currently going on in which telephone callers are claiming to be members of the State Police or affiliated with us, and are soliciting money for various reasons.
Please be advised that these claims are fraudulent. The State Police are not conducting any fundraisers and do not conduct phone solicitations for anything.
If you get such a call, please hang up.
In fact, if you receive any call from someone soliciting money for any purpose, claiming to be from any source, do not provide any personal or financial information.
If it sounds like a legitimate charity you might want to support, first check with the Massachusetts Secretary of State's Corporation Division at (617) 727-9640 to make sure that the organization is, in fact, legitimate.