Since the weekend, we've had 13 suspicious fires, of which, 12 have been ruled arson.

A national arson team is in Seattle now to try to stop the arsonist.

Half a city block was on fire when a Phinney Ridge construction site went up in flames Saturday night. Four floors of condos devoured, and the fire was too big for local investigators to handle.

That's why Seattle Fire requested help and got 15 members of an elite ATF National Response Team.

Their resume is impressive: the Oklahoma City bombing, WTC bombings, and 9-11.

A crane is the only way they can safely collect fire debris.

"We'll remove a layer of debris and examine it for any evidence and move on to the next layer until we found where the origin of the fire is," said Special Agent Peter O'Connor with the ATF National Response Team.

Structural engineers have deemed parts of the building safe, giving fire investigators some limited access to the ground level.

The team of blue T-shirts with ATF in bright yellow is just what nearby storeowner Anthony Dell needed to see.

"ATF, we got the best guys around," he said.

It's been three days since the fire, and Dell says he's still in shock; his antique storefront is charred.

Investigators told all the merchants across the street to shut down until further notice. It's fueled their anger -- not against investigators but a possible arsonist.

"They gotta catch him and exterminate him and make an example," Dell said.

Investigators do not know yet if this fire was deliberately set, but O'Connor says the timing was certainly suspicious.

But with 14 arsons in just a few days, every fire seems suspicious - and every firefighter is a little edgy

"When someone is purposely out there setting fires it puts everyone on edge," said Melanie Granfors with the Shoreline Fire Department.

Not ignoring other fire investigations, feds are helping with the entire arson investigation.

Officials say the have interviewed persons of interest and have received a lot of tips on the fire.

If you have a tip or know who has been setting the fires, you're asked to call 1-800-55-ARSON.