A Three Rivers Ambulance Authority Supervisor truck hit a person early Friday morning.  The accident happened downtown on  Brackenridge Street.  When police got to the scene they found a TRAA medic helping the guy out and police believe they think they know what had happened.  They say, the man had been involved in an argument with a woman at which time he got out of their car and jumped on the hood.  When he got off the car the woman drove away. Police believe as the man was walking down the street he may have jumped in front of the TRAA vehicle. He was taken to the hospital in serious condition, but has since been downgraded to critical.