Details are emerging about the device used during Monday's explosion in a New York City subway tunnel. Investigative Reporter Myles Miller has some of the early details.

Officials say the suspect Akayed Ullah received all his information on how to build the pipe bomb used in Monday's explosion online.

"Fortunately for us, the bomb partially detonated," New York Gov. Andrew Cuomo said. "It was not a sophisticated device."

Sources close to the investigation said the elements left behind can help investigators put together a post blast analysis to figure out how and when the bomb was created.

"He did detonate it, but it did not fully have the effect that he was hoping for," Cuomo said. "The explosive chemical did ignite, it was in a pipe, but the pipe itself did not explode. So he wound up hurting himself."

Investigators currently believe a cell phone was used as a trigger for the device and that the suspect was reaching out for that phone even as he lay wounded, surrounded by Port Authority police officers.

"It was affixed to his person with a combination of Velcro and zip ties. The bomb squad is in the process now, along with the FBI special agent bomb technicians," John Miller, the NYPD's Deputy Commissioner of Intelligence and Counterterrorism said earlier Monday. "Of processing that crime scene with others."

"They're going to gather up those pieces and we'll have a better idea of what the device was put together with and what was inside it," Miller added.

Law enforcement sources said it didn't come as a surprise that the suspect learned how to make the pipe bomb online, given the amount of step-by-step videos that have been used in previous domestic terrorist attack in New York, such as the one used in 2016 Chelsea bombing. The suspect, Ahmad Khan Rahimi, built a homemade pressure cooker from an article he found online.