Rec'd email Call Support: 1-866-602-4279 We've noticed that someone attempted to fill out a tax return using your information with a different account. Is this scam?

Yes, it is a scam.

As my colleague Lisa responded to another client a year ago who was contacted by the same phone number,

I called this number and it is not TurboTax.  It is a pre-recorded advertisement.  I am going to report this our security center.  However, please do not respond to any further emails or calls from these people.

The following link may give you more information on how seriously TurboTax takes your security seriously:

https://turbotax.intuit.com/best-tax-software/secure-online-tax-prep/

Source: https://ttlc.intuit.com/questions/4280607-is-this-a-scam-rec-d-email-telling-me-to-call-1-866-602-42...

I will report it again to our security. 

I have received the same email.