WOODBURN, Ore. -- With bagpipes playing and a light snow falling, hundreds of law enforcement officers have gathered in Salem to mourn 51-year-old police Capt. Tom Tennant, killed a week ago in a bank bombing.

A procession that police estimate contained 300 to 400 law enforcement vehicles crawled at 20 mph along state highways Friday from Woodburn, where Tennant served 28 years. At the Salem Armory, six officers carried the flag-draped casket, followed by family members.

 Photos: Memorial

Photo courtesy: Woodburn Police Department

Capt. Tom Tennant, 51, was a 20-year veteran of the Woodburn police force. He was killed in the bank explosion Dec. 12.

Friday's public memorial honors Woodburn Police Capt. Tom Tennant. Hundreds of officers took part in the procession, despite icy conditions on area roads.

The memorial for OSP Sr. Trooper Bill Hakim, also killed in the explosion, was scheduled for 11 a.m. Saturday, Dec. 20. It begins at the Salem Armory and will be followed by a procession to the Department of Public Safety Standards and Training.

Gov. Kulongoski has ordered all state flags at public institutions be flown at half-staff on Friday, Dec. 19, in honor of Capt. Tennant and on Saturday, Dec. 20, for Sr. Trooper Hakim.

"Together, these two men served Oregon for more than 30 years, putting their lives on the line daily so our citizens could be safe and secure in their homes and communities," Kulongoski said.

There was still no indication as to the motive behind a deadly exlposion that killed the two officers and critically injured a police chief at a small Woodburn bank branch Dec. 12.

 Background: Father & son bomb suspects

Oregon Gov. Ted Kulongoski denounced the bombing, saying the tragedy "will forever be remembered in our state's history."

 Also: Kulongoski issues statement on bombing

The explosion happened at the West Coast Bank on the Newberg-214 Highway just before 5:30 p.m. Friday, Dec. 12. Officers were on the scene investigating a report of a suspicious device when the explosion occurred.

A bank employee found the bomb in bushes outside the bank, and officers took it inside, when it exploded, according to the Associated Press.

Details released on Dec. 16 indicated that an Oregon State Police bomb technician inspected and X-rayed the device.

Court documents said bomb technician Bill Hakim was "confident that it was a hoax device and that it could be taken apart to be placed into evidence."

Hakim brought the green box into the bank to work on it, with help from Woodburn Police Department Capt. Tom Tennant and Woodburn Chief of Police Scott Russell, and it detonated.

Hakim and Tennant, both 51 years old, were killed in the blast.

Russell, 46, was badly injured.

A female bank employee, West Coast Bank Customer Service Manager Laurie Ann Perkett, received minor injuries, including lacerations on her right leg and bomb shrapnel embedded to the bone below her knee. She was treated and released from Salem Hospital.

Threatening phone call leads police to banks
On Friday morning, Dec. 12, a Woodburn-area Wells Fargo Bank received a threatening phone call from an unknown person.

According to a probable cause statement, last Friday at 10:19 a.m. a man called in a bomb threat to the Wells Fargo Bank in Woodburn, which is nearby the West Coast Bank branch. The man said "if 'they' didn't leave the building, all of them would die," the court document states.

The man also said a cell phone would be found next to a garbage can, and that he would give further instructions on it. The man also said he would be calling the West Coast Bank.

Local police officers arrived at the Wells Fargo building, opened a garbage bin, and spotted a cell phone on top of what appeared to be a package. Hakim and an FBI bomb technician were called. They examined the package and cell phone, and determined it was a hoax device.

Photo courtesy: Oregon State Police

William "Bill" Hakim died Friday, Dec. 12, while investigating the Woodburn bank bombing.

While investigators were in the area, another suspicious device detonated.

State police said the first device, discovered by police after the suspicious phone call, was determined not to be dangerous. The second device, which was discovered by a bank employee, did detonate.

"This individual took the life of two police officers, critically injured the chief of police, and potentially could have taken the lives of bank employees inside," Oregon State Police Lt. Hastings said. "If it takes a $35,000 reward, or if that reward grows, to break the case open then it's money well spent."

Hakim became the second bomb technician in Oregon State Police history to be killed in the line of duty.

Marion County sheriffs described Hakim as a dedicated family man with wife and two teenaged children.

 More: Hakim survived by wife, two children

Woodburn Police Sgt. Jason Tlusty became emotional describing Capt. Tennant, who also was killed in the blast.

Tlusty described Tennant, 51, as an active community member "who would do anything to help those in need."

Tennant was a 28-year veteran of the Woodburn Police Department.

Photo courtesy: Woodburn Police Department

Woodburn Chief of Police Scott Russell, 46, was badly injured in the bank bomb explosion.

Nearly a full day into the investigation authorities said it remained unclear whether the two devices were related.

Police said the inside of the bank was extensively damaged but declined to describe the bomb in detail, except to say it was "powerful."

West Coast Bank President and CEO Robert Sznewajs said he didn't know of any grudges to motivate the bombing.

"We're not aware of anything," he said.

The Associated Press contributed to this report.