An explosion near New York City’s Port Authority Bus Terminal shut down parts of the city’s transportation system and prompted a massive emergency response Monday in Midtown Manhattan. The suspect in the attack was identified as 27-year-old Akayed Ullah, officials said in a press conference.  He was taken into police custody after the bombing.

Ullah was from Bangladesh and had been in the United States for seven years and lived in Brooklyn, ABC News correspondent Aaron Katersky reported. NYPD officers and FBI agents were reportedly looking into his Brooklyn home as part of the investigation.

When asked whether the suspect was connected to ISIS, authorities said Ullah "made statements," but that the details were part of an ongoing investigation. Authorities confirmed during the press conference the incident was an attempted terror attack.

It was unclear whether the suspect was cooperating with authorities. He was believed to be at Bellevue Hospital. It remained unknown whether the suspect acted alone or if others were involved, though initial signs pointed to him being a lone actor and authorities said there was no other credible threat at this time.

“It’s fairly clear at this moment that this was an apparent terrorist attack,” former NYPD Police Commissioner Bill Bratton told WNBC.

Initial reports said the explosion was the result of an explosive vest or a pipe bomb that went off prematurely, police said. Police said the suspect was injured as a result, though the extent of his injuries had not yet been disclosed. Ullah had wounds to his stomach, authorities confirmed. Four people in total were injured, the FDNY said.  The injuries appeared to be as minor as ringing in the ears and headaches.

Ullah was reportedly a cab driver and perpetrated the act as a form of revenge, the New York Post reported

“They’ve been bombing in my country and I wanted to do damage here,” he reportedly said, according to the Post, who cited law enforcement officials.

Authorities said they were looking into video taken at the scene which appeared to show Ullah in the moments before the bomb was detonated. The video, taken in a walkway connecting the subway to the Port Authority Bust Terminal, appeared to show Ullah wearing some sort of explosive device.

A witness described two explosions which he heard through his headphones at about 7:45 a.m.

“From what I saw it sounded like it came from the subway, but I’m just guessing,” Francisco Ramirez told CNN. “It was two distinct explosions seconds from each other. As I was making my way toward the outside, I kept getting shoved by cops and there were cops at every entrance blocking and there was police and SWAT everywhere. It was scary. It was just a lot of chaos.”

The FBI’s Joint Terrorism Task Force joined the scene alongside the New York City Police Department and the New York City Fire Department to investigate the situation.

Both President Donald Trump and New York City Mayor Bill de Blasio were briefed on the situation. The subway system was significantly affected by the explosion: The 1, 2, 3, A, C, E, N, Q, R, W and 7 train lines all experienced delays following the incident.