The afternoon of June 10, 1999, Bellingham Police Chief Don Pierce was on the 16th fairway at Bellingham Golf and Country Club, playing host to a law enforcement visitor.
Pierce doesn't recall hearing the boom of the explosion, but something caught his attention.
He glanced up and saw massive, dark, angry clouds roiling high into the sky.
"You knew instantly, this is a big deal," Pierce said.
Premium content for only $0.99
For the most comprehensive local coverage, subscribe today.
He called the police station, then drove to the command post by Woburn and Iowa streets, near where a gasoline-fueled fire had flashed down Whatcom Creek.
While firefighters and medics fought the blaze and looked for victims, police kept motorists and curious citizens away from Whatcom Falls Park.
"As I was standing there, none of it made any sense, because creeks don't catch on fire," said Pierce, who stepped down as Bellingham's chief of police in early 2000. "I don't think I knew there was a gas pipeline that ran under there."
That early lack of information raised immediate questions: What was burning? Was the smoke toxic? Should people in the area be evacuated, or could they safely stay put?
Then an employee of Olympic Pipe Line Co. arrived and said the company's pipeline full of gasoline had apparently ruptured. Pierce then knew that people wouldn't have to be evacuated.
But the question of an evacuation came up again later that night. Monitors showed that high concentrations of explosive vapors had collected in utility pipes under downtown.
Could the vapors ignite? What would happen if they did? Should the heart of downtown be evacuated? Where would people go? Would the evacuation create major problems of its own?
As Pierce and other officials discussed those questions and made plans, the vapors began to subside. The danger passed.
By then, the tragic nature of the explosion was clear. Two young boys, Wade King and Stephen Tsiorvas, had been found alive, but badly burned. Both died the next day.
When Pierce saw a picture of the vehicle left by another person in the park, he knew it belonged to Liam Wood, a friend of his teen-age son.
Looking back, Pierce said the emergency broadcast system should have been activated immediately to alert the public, and said an emergency-response headquarters could have been opened sooner to coordinate the many agencies involved. Still, Pierce said agencies responded well.
"Everybody pitched in and did what they needed to do," he said.
The tragedy remains one of the most memorable incidents of Pierce's four decades in law enforcement. Now executive director of the Washington Association of Sheriffs and Police Chiefs, he said the disaster still comes up for discussion at workshops for emergency responders.
"The chill goes down my spine," he said.