The first calls came into the Richmond Police Department, the Contra Costa County Fire District and the sheriff's department at 6:35 p.m. Monday. From the beginning, there was no mistaking the seriousness of the situation.
"Inform CHP we already have people stopping on 580 on the shoulder to watch the fire," a dispatcher can be heard saying.
Along with the first responders -- the fire and ambulance crews -- EPA agents and Contra Costa County Hazardous Materials staff rushed to the scene.
"When people saw it, there's a lot of black smoke; that's usually a lot of particulates in that smoke," Contra Costa Health Services Environmental Health Chief Randy Sawyer said. "If you breathe that in, it can lodge in your lungs and irritate your throat."
Sawyer says 450 neighbors went to the hospital complaining of respiratory problems.
But, the question now is -- did Chevron workers act quickly enough to fix what at first appeared to be a minor leak of diesel fuel?
"They were saying it was just drips, like 20 drips a minute or something, so it was very small, so they were getting a team together to determine how they were going to either block off so they could repair the line or put a patch on the line," Sawyer said.
The workers discovered the leak after 4:15 in the afternoon. It took them more than two hours to evaluate the problem and devise a plan to fix it. At 6:30 p.m., they tore off the pipe's insulation and poured cooling water on it. The pipe failed completely. The workers evacuated, and Unit 4 went up in flames.
At a news conference Tuesday afternoon, Chevron's head of emergency services defended workers taking two hours to address the leak.
"We're evaluating that actual leak; we're looking to see what's causing it, where it is, how we can isolate it," Mark Ayers said. "We're looking at all those different options. It's during that two hour period, while we were evaluating that leak to determine what exactly it is we need to do that it got worse."
An oil industry consultant in Houston says shutting down a line in a refinery is not as easy as turning off a faucet.
"Two hours is a very expected time frame in which to make an assessment," Michael Taube said. "You're running thousands of gallons of product through this line over the course of a day and you just can't stop it suddenly without having a potentially severe impact upstream."
This is the third serious fire at the Chevron refinery in the past 13 years.
The failure of an improperly attached pipe caused a blaze in January 2007. One refinery worker suffered minor burns. In March 1999, a leaking pipe created a vapor cloud that exploded and burned. Four hundred neighbors went to the hospital during that incident.
Cal/OSHA and Contra Costa Health Services officials are investigating now. One question they need to address -- did the process of pouring cool water on the hot pipe cause it to rupture?