The man accused of detonating an explosive in the New York City subway system wrote on Facebook the morning of his alleged attack, “Trump you failed to protect your nation," according to the federal complaint against him.

Akayed Ullah, 27, an immigrant from Bangladesh, is accused of setting off the homemade bomb in an underground passageway near the Port Authority Bus Terminal Monday morning, sending commuters scrambling to evacuate the major transit hub just blocks from Times Square.

TLC

“He intended to set it off in that corridor,” New York Police Department counterterrorism chief James Waters told ABC News. “We know that terrorist organizations are somewhat fascinated by the subway system.”

Despite the rush-hour crowds, only five people suffered minor injuries, officials said.

Ullah, who was badly injured from the explosion, allegedly told investigators he consumed Islamic State and al Qaeda propaganda, a law enforcement official told ABC News. There is no evidence he received funding or specific direction from any overseas group.

Ullah is charged with five federal counts, including use of a weapon of mass destruction and bombing a place of public use.

According to the charging document Ullah made statements that indicated he “was inspired by ISIS to carry out” the attack and said, “I did it for the Islamic State.”

Mike Segar/Reuters

Ullah built the bomb in his Brooklyn home a week before the attack and began compiling materials two to three weeks earlier, according to the complaint.

A law enforcement source said the homemade bomb was built from a 12-inch-long pipe, black powder and rigged with a 9-volt battery and a wire that came from a Christmas light. The pipe had nails stuffed into it, the source said, and it had the ability to impose more injuries than it did.

“He did follow some of the instructions that you can find readily online, unfortunately, to create such a device,” Waters said. “A Christmas light bulb is one of those components.”

The charging document said law enforcement personnel found a 9-volt battery inside Ullah’s pants pocket, wires connected to the battery running under his jacket and fragments of metal pipe.  There was also a remnant of what appeared to be a Christmas tree light bulb attached to the wires.

The FBI lab in Quantico, Virginia, and the NYPD bomb squad are analyzing components of the explosive.

Bryan R. Smith/AFP/Getty Images

Because the device was strapped to the suspect, the assumption is he had been prepared to die as a suicide bomber, a source said.

Ullah "was not on the FBI’s radar nor was he on the NYPD’s radar," chef Waters said.

“We’re going to piece together who he is, what he’s all about, who are his family members, his associates, his contacts, why did he do this,” Waters said.