Pierce County organizers say the public should be prepared to take buses Tuesday to a Tacoma Dome memorial service for the four Lakewood police officers gunned down in the deadliest attack on law enforcement in state history.

The service is expected to draw more than 20,000 people and fill the Tacoma Dome. Organizers are encouraging the public to watch the service from an overflow location in Parkland.

General seating at the Tacoma Dome will be limited because of the number of law-enforcement and other public-safety officials attending from all across the country and beyond.

The public is encouraged to consider picking a spot along the processional route and watching the service from an alternative location, organizers say. Local network-television stations plan to air the service live.

The procession will begin at 10 a.m. at the north gate of McChord Air Force Base and will proceed through Lakewood to the police department, where Lakewood police and families of the slain officers will join the procession.

Doors to the Tacoma Dome will open at 11 a.m., and the service will start at 1 p.m.

Those planning to attend the service at the Tacoma Dome also may have trouble finding parking because most of the parking spaces will be reserved for procession vehicles and emergency vehicles, organizers said. The public is encouraged to use two off-site parking areas.

From 10:30 a.m. until noon Tuesday, Pierce Transit will provide free bus service from the two off-site lots to the Tacoma Dome, and resume service back to the lots after the ceremony. The two off-site parking areas are Cheney Stadium, 2502 South Tyler St. in Tacoma, and the north parking lot of the Tacoma Mall.

The public also can watch the service from Pacific Lutheran University's Olson Auditorium in Parkland. The auditorium, at 124th Street South and 10th Avenue South, will open at 9 a.m.

Parking for those going to the auditorium is at the Church For All Nations, 111 112th St. E. A shuttle will run from 9:30 a.m. to 1 p.m., and will resume after the service to transport people back to the lot.