Pressure-cooker and pipe bombs, constructed with easily bought and unregulated materials and linked to cellphones, were used in the recent explosions in New York and New Jersey, federal investigators say.
While officials have not connected the attacks to international terrorism, the use of pressure cookers as explosive devices has been recognized for years by counterterrorism experts because it has been touted by al-Qaeda. Similarly constructed devices have been deployed by terrorists in bombings around the world, from the 2013 Boston Marathon to attacks in the Middle East, South Asia and North Africa.
Pressure cookers have also been tied to al-Qaeda because the first edition of Inspire magazine, produced by the group’s Yemeni affiliate, included an article teaching people how to make pressure-cooker bombs. It was titled “Make a bomb in the kitchen of your Mom.” The same 2010 issue also explained, with step-by-step photographs, how to assemble pipe bombs.
In 2004, the Department of Homeland Security sent a bulletin, “Potential Terrorist Use of Pressure Cookers,” to law enforcement. It warned that pressure cookers, “a common cooking utensil,” were often overlooked in searches of vehicles, houses or people crossing U.S. borders.
The bulletin also said that explosive material inside a pressure cooker could be detonated “using simple electronic components including, but not limited to, digital watches, garage door openers, cell phones or pagers.”
The first pressure-cooker bomb in New York this weekend, which exploded on 23rd Street in Manhattan on Saturday night, contained Tannerite, a substance that includes ammonium nitrate and is used primarily for making exploding targets for firearms practice. Tannerite is not regulated by the Bureau of Alcohol, Tobacco, Firearms and Explosives. It consists of two components that are allowed to be legally purchased because neither is an explosive by itself.
Common pressure cookers of the kind found at most discount stores were used for the two bombs that went off at the Boston Marathon. They were armed with simple detonators and were packed with an explosive, along with BBs, nails and pellets to cause more casualties. Investigators say the first New York bomb contained similar material.
The second explosive device, found on 27th Street by passersby who called the police, was also a pressure-cooker-type bomb with wiring, according to law enforcement officials. It did not detonate.
About 11 hours earlier, at about 9:30 a.m., pipe bombs exploded in a garbage can shortly before a charity 5K race in Seaside Park, N.J., on the Jersey Shore, to benefit Marines and Navy sailors. Such bombs use a tightly sealed section of pipe to hold explosive material. The material found inside the New Jersey pipe bombs was black powder, according to law enforcement officials.
The three pipe bombs were constructed using Christmas lights. A cellphone can be wired to the lights, which serve as a match to ignite the explosives when a call is made to the phone, explained one explosives expert, who was not authorized to publicly discuss the issue and so spoke on the condition of anonymity. The cellphone can also be used as a timer to set off the bomb.
The Boston Marathon bombers, Dzhokhar and Tamerlan Tsarnaev, also used Christmas lights as improvised fuses.
The multiple explosive devices that were found in a backpack Sunday night near a train station in Elizabeth, N.J., also included pipe bombs.
New York police officials said the pressure-cooker-type device found on 27th Street was rendered safe at a facility in the Bronx. That device and materials from Seaside Park were sent to the FBI’s lab in Quantico, Va., where they will be analyzed, along with the remnants of the device that exploded in New York, authorities said.
The FBI has linked a suspect, Ahmad Khan Rahami, to the New York and New Jersey bombs. Rahami, 28, was arrested Monday in Linden, N.J., after being wounded in a shootout with police. He was taken to a hospital.
Rep. Peter T. King (R-N.Y.) said the FBI told him that the bomber made similar mistakes with more than one of the devices that caused them not to detonate properly.
King said the FBI used fingerprints and a cellphone attached to one of the pressure cookers to track down another cellphone that belonged to the suspect.
“FBI took me into the crime scene” on 27th Street, King said. “They must have had 40 to 50 personnel on hands and knees. It’s an incredible scene. Every single ball bearing and piece of evidence, they’re putting a little white paper cone over it. So you just see this field littered in dozens of white cones.”
Law enforcement officials said the New York bombing, which injured more than two dozen people, could have been much worse. Because the bomber placed the device under a garbage bin, the can took the force of the blast and absorbed the fragmentation of the shrapnel.
“The dumpster that was exploded was thrown down the street 175 feet, to give you an idea of how powerful it was,” King said. “You had ball bearings everywhere. If the streets had been crowded, there would have been bad injuries. There were windows broken as high as the third floor.”