Earlier, the widow of Lt. Aaron Allan visited the National Law Enforcement Memorial to view her husband's name. It includes a list of names engraved along a pair of 304-foot-long walls, which grows longer each spring when the names of fallen officers are added.
Near the end of the ceremony, people in the audience held up blue glow sticks, signifying the thin blue line law enforcement officers walk on every day.
National Police Week has evolved over the years, according to the Yolo County District Attorney's Office.
On Thursday, the Federal Bureau of Investigation released the Law Enforcement Officers Killed and Assaulted (LEOKA) report of 2017.
The other two officers honors were Lt. Albert Grosskopf with the Milwaukee Police Department - he died in 1943 - and Officer Charles Freiherr with the Sheboygan Police Department.More news: UN nuclear watchdog's inspections chief quits after US withdrawal from Iran deal
Weiland was shot and killed in the line of duty during the March 22nd shooting rampage in the Wausau area.
Leo was killed while responding to a domestic incident on October 22.
This is a time for our country to salute the courageous men and women who serve and protect towns, cities, states, and most importantly citizens across the country. He pointed out that the 129 officers to died on the job in 2017 represented the second-smallest figure since 1959. So he and his wife Lora created this service.
Sunday's vigil is being held ahead of National Peace Officers Memorial Day, which is held annually on May 15 to honor law enforcement officers killed or disabled in the line of duty. The evening's program also featured moving musical tributes and a special recognition of survivors of fallen officers.
The Candlelight Vigil is one of many commemorative events taking place in the nation's capital during National Police Week 2018.