Click here to see a slideshow of the services.

About 20,000 mourners, mostly members of law enforcement from Washington state and across the country, honored four slain officers who were remembered Tuesday as heroes and loving family members.

A procession of 2,000 cars followed the flag-draped caskets of Sgt. Mark Renninger and Officers Ronald Owens, Tina Griswold, and Greg Richards to the Tacoma Dome, where the memorial service was held. Several candlelight vigils have been held for the officers since the shooting on Nov. 29, but Tuesday's memorial service and procession are believed to be the largest in state history.

"I would have gone through any door with Mark and I trusted him with any mission," said Assistant Chief Mike Villa, of the Tukwila Police Department, where Renninger once worked. "I will not forget Mark, the good that he did or the life that he led."

The Lakewood officers were killed by a lone gunman Nov. 29 before the start of their shift. Authorities say Maurice Clemmons singled them out and spared employees and other customers at the coffee shop in Parkland, a Tacoma suburb about 35 miles south of Seattle.

'Our dad was a hero'

Clemmons was shot to death last week by a Seattle police officer after a two-day manhunt. Prosecutors said he received help from family and friends, and seven people have been arrested.

"Our dad was a hero to many even long before he became a policeman," said Richard's teenage son, Austin. "The way he lived his life spoke volumes."

Lori Lightfoot and Sheila Chandler, both police detectives from Fresno, Calif., were among officers who traveled from as far away as New York, Chicago and Canada for the service. They said the deaths of the four Lakewood officers brought back memories of four Oakland police officers killed during a traffic stop and a shootout in March.

"It's just disbelief," Lightfoot said. "It's unbelievable that it could happen again."

Gov. Chris Gregoire said that the sacrifice would not be forgotten, adding: "We owe the children of these officers, all nine of them, a present and a future that is safe and secure."

Pamela Battersby, a friend and co-worker of Griswold, said Griswold liked dressing up and going out, but that she was also a tomboy rode motorcycles. She met not only the women's standards on physical fitness tests "but the men's as well," Battersby said.

The elder sister of Owens said that her brother followed their late father into law enforcement.

"They were two peas in a pod," said Ronda LeFrancois. "I know they are in heaven together."

'Something this tragic'

Cpl. Jack Hundial, of Surrey, British Columbia, was one of 1,000 Royal Canadian Mounted Police in attendance. He said he and his colleagues wanted to show their support because "it could have been any of us."

"I think about their families," he said. "I don't think you ever find true closure for something this tragic."

Floral arrangements lined the stage at the sports arena, as well as two motorcycles, a drum set and a NASCAR race car. Griswold and Owens both loved motorcycles, Owens played the drums, and Renninger was a big NASCAR fan, according to Lakewood Mayor Dennis Fountain.

The service included a 25-minute photo slideshow of the officers. It ended with a bell rung 21 times and a presentation of the flags from the officers' caskets to the families of the fallen.

Owens and Richards will be buried during private funerals Wednesday. Renninger will be flown back to his home state of Pennsylvania on Wednesday for burial.

Here's a brief biography of each of the four officers:

Sgt. Mark Renninger

Renninger was described as a cop's cop: A tough guy who excelled at his job and was regarded as a leader and teacher in the close-knit Lakewood police force.

"He was the most competent and tactically proficient man I ever knew in police work. I do not say this because he was killed and that is something you should say," Lakewood police union president Brian Wurts said. "Everyone in our department and all who knew Mark know this was true."

Relatives said Renninger, who grew up in Bethlehem, Pa., came to Washington state through military service. The East Coast native was blunt-spoken but "never belittled anyone," Wurts said.

"Mark had that spark that made you like him and respect him. He was truly a rock in our department, someone you always counted on," Wurts wrote.

The union said Renninger was married with three children.

Officer Tina Griswold

Her sister, Tiffiny Ryan, said Griswold liked to cook, ride her dirt bike and was a certified diver.

"My worst nightmare has come true," Ryan told reporters on Monday. "I can't tell you how painful it is to lose my sister."

Griswold knew she wanted to be a police officer by the time she finished high school, a weeping Ryan said.

Their father is a retired police officer, while their mother was an administrative assistant at the Washington Supreme Court, Ryan said.

Tina Griswold began working in law enforcement as a dispatcher in Shelton, then became a police officer in Shelton and Lacey before going to work in Lakewood five years ago, Ryan said.

Griswold also has a 21-year-old daughter and a 7-year-old son, Ryan said.

Officer Ronald Owens

Relatives said Owens - known to friends and family as Ronnie - was a lifelong resident of Parkland, the Tacoma suburb where he was killed. The police union said Owens has a daughter.

Wurts said Owens' fun-loving personality "made everyone around him feel positive."

He "was the laid-back, dirt-bike-riding, surfer-hair-having cop you would always want at a party or with you on any call," Wurts said. "Though he had a laid-back perspective, he was sharp and an extremely dedicated and hard worker."

Owens was a Washington State Patrol trooper from 1997 until 2004, when he left to join the Lakewood police, Patrol Chief John Batiste said.

"While we have many ranks and honors that we offer for exemplary service, the most coveted honor is to simply be respected by your colleagues as 'a good troop,'" Batiste said. "Ron Owens was most definitely a good troop."

Officer Greg Richards

Richards liked nothing better than spending time with his wife Kelly and three children, the union president said.

Richards enjoyed music in his spare time, playing drums in a rock band that performed this summer at a charity event for a hospitalized fellow-officer.

Richards was liked by everyone he met, sister-in-law Melanie Burwell said. Even though the family knew his job could be dangerous, his death was a shock, she said.