"Crude, simple" device in Chelsea blast used household materials

Bomb material clues

NEW YORK -- Sources tell CBS News that the pressure-cooker device that exploded in Manhattan on Saturday evening contained residue of a material called Tannerite, a legal explosive made up of ammonium nitrate and aluminum powder. 

What is known about Ahmad Khan Rahami

“It was a very crude, simple device,” Former FBI agent Manny Gomez said. “Put in some metal devices, whether it’s ball bearings, screws, nails, et cetera. It turns into a huge detonation, that obviously could hurt. kill, or maim many people.”

Gomez told CBS News’ Anna Werner the bomb was similar to those used in the Boston Marathon attack​. 

Experts say terrorists commonly use the crude bombs overseas, but a former FBI bomb specialist told CBS News the use of them has “ramped up substantially” in the U.S. 

Directions to make them can be found on the internet.

The devices use hard-to-trace, easily-obtained explosives packed into cheap containers. All that’s required is an electrical trigger, like a cell phone, to set them off.

A view of a mangled dumpster at the site of an explosion that occurred on Saturday night in the Chelsea neighborhood of New York, September 18, 2016.  Justin Lane/Pool/REUTERS

“In this case it was an old fashion type of flip cell phone that the caller simply calls. It sends an electric shock through the wires, it explodes the pressure cooker,” Gomez said.

Experts say they’ve also seen the use of common Christmas lights as fuses inside homemade devices in other American bombing incidents.