Yes it is a scam or at the very least an illegal debt collection extortion attempt. You NEVER get calls warning you of arrest warrants or a summons about to be served. Any arrest warrant would be known to your local law enforcement office and any court summons would be on file with the Clerk of Courts for your county of residence. You can easily contact both offices to verify that there is nothing there regarding you.
It's a scam. Debt is civil, not criminal, so even if you've defaulted on a loan, you cannot be arrested. Email is not a legally valid means of "serving" anyone either. This is just another debt scammer trying to part you from your hard-earned money. You can make a complaint to the FBI at their Internet Crime Complaint Center - www.ic3.gov. Otherwise, delete and ignore the emails, and whatever you do, DON'T open any attachments - they may contain malware or put spyware or keyloggers on your computer!