As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT, THE LEFT ENGINE FIRE WARNING SOUNDED. FOLLOWED ENGINE FIRE PROCEDURE AND FIRE INDICATION CONTINUED. DISCHARGED BOTH FIRE BOTTLES, RETURNED TO MSP AND LANDED WITHOUT INCIDENT. FOUND BOTH LOOPS SHORTED. REPLACED FIRE DETECTION LOOP, RUNUP AND OPERATIONAL CHECK OK.