Nearly 20,000 members of law enforcement gathered at the Tacoma Dome on Tuesday to honor their fallen brothers and sister during a memorial ceremony that reinforced the dangers of patrol duty.

Officers from Washington state, the rest of the nation, and Canada filled the venue following a 2,000-vehicle morning procession.

The service, which was broadcast on network television and streamed online by several Seattle-area TV affiliates, moved at a fairly brisk pace, as speakers recounted memories of the fallen officers.

The memorial service featured tributes to Sgt. Mark Renninger, Tina Griswold, Ronald Owens, and Greg Richards.

Renninger, 39, was remembered as a proficient SWAT officer who taught classes in basic SWAT, breeching, and advanced tactics for the Washington Tactical Officers Association.

"Mark was a tremendous patrol officer but his calling was SWAT," said Mike Villa, a former partner and assistant chief with the Tukwila Police Department. "Honor, dedication, courage. Mark embodied these qualities."

Renninger worked for that department prior to joining the Lakewood Police Department.

Griswold, 40, was remembered as a tomboy who enjoyed mixed martial arts and was a proud member of the National Rifle Association.

Owens, 37, enjoyed riding his motorcycle while off duty.

Perhaps the most touching moment came when Richards' three children spoke about their father as a "hero to many." Richards appreciated life's simpler pleasures (such as mayonnaise) and taught his children never to bear grudges against others, they said.

In addition to the eulogies, mourners gathered to watch a video tribute to the officers. Floral arrangements lined the venue's stage, along with a memento representing each officer. The mementos included a NASCAR race car because Renninger was a fan of the sport, two motorcycles for Griswold and Owens, and a drum kit for Richards.

The officers were shot and killed by a man posing as a customer in a Seattle-area coffeeshop on Nov. 29 as they worked on laptops and prepared for their shift. Seattle officer Benjamin Kelly shot the officers' killer, Maurice Clemmons, who was armed with a handgun he had taken from one of his victims.