WATCH: Memphis Cop Killed In Petty Crime Pot Bust

MEMPHIS — (CNN) It started as a regular traffic stop on a weekend night in Tennessee. Officer Sean Bolton saw an illegally parked car on the streets of Memphis, pulled up in front of it and shone his spotlight.

When he approached the vehicle, a passenger confronted him.

A struggle ensued, and the passenger shot Bolton multiple times, authorities said. The car drove off, leaving the officer for the dead.

“Officer Bolton apparently interrupted some sort of drug transaction,” Memphis Police Director Toney Armstrong said. “A digital scale and a small baggie of marijuana … were located inside of the vehicle.”

Memphis police identified Tremaine Wilbourn, 29, as the suspect. He is on the run, and considered armed and dangerous.

The violence was senseless given how mundane the stop was, Armstrong said.

“We’re talking about less than 2 grams of marijuana. You’re talking about a misdemeanor citation,” he said. “We probably would not have even transported for that.”

Nearby residents heard the gunshots and used Bolton’s radio to call for help, which arrived and took him to the hospital in critical condition. He was later pronounced dead.

Armstrong described the suspect as a “coward.”

“You gunned down, you murdered a police officer, for less than 2 grams of marijuana,” he said. ” You literally destroyed a family.”

Friends described the Iraq veteran as a gentle man who did not believe in using force.

“For a police officer to have that kind of temperament, and to take such a cautious approach to the use of force, he was a credit to the uniform,” his friend Steve Clements told the Commercial Appeal in Memphis.

Bolton was quiet, and loved to read and go to the gym, Minda Klitzner told the paper.

So much so, he’d read in the car during road trips.

Bolton, 33, is one of 19 officers killed nationwide this year by violent suspects. The deaths at the hands of suspects run the gamut — veterans and rookie officers — and span the nation — from Georgia to California

“Last night, we lost not only an officer, but a great man, a dedicated servant to our community, and a family member,” Armstrong said.

This is the third time a Memphis police officer has been killed in the past four years.

The vehicle’s driver later turned himself into police and was released without charge.

Authorities are offering a $10,000 reward for information leading to Wilbourn’s arrest. He is out on supervised release for a 121-month sentence for robbery, according to Armstrong.

Bolton was turning 34 this week.