There remains no indication the captured prime suspect in the New York and New Jersey bombings was operating as part of a terror cell with no other individual currently being sought over the plots, US authorities have said at a joint news conference.
An FBI spokesperson confirmed detectives were working to trace whether Ahmad Khan Rahami was part of an extremist network as New York Mayor Bill de Blasio confirmed "we now have every reason to believe" the weekend blast in Manhattan was an "act of terror".
NYPD chief James P O'Neill said two officers were injured during the capture of the "dangerous individual" Rahami and said the investigation now centred on whether he acted alone and on his possible motivations.
Police Commissioner O'Neill said the investigation remains "very much active" despite the capture of the main suspect in a shootout.
Mr De Blasio said authorities were not looking for any other individual at this stage of the investigation though the NYPD are still keen to speak to two people seen close to the scene of Saturday's blast in the Chelsea district, who they regard as "witnesses" in the case.
The FBI said five individuals questioned on Sunday night are no longer in custody.
Authorities are investigating whether Ahmad Rahami, who was not on US counter-terrorism lists, acted alone or as part of a terror cell.
Investigators studying CCTV footage may have identified the same man at each location, law enforcement sources reported to have said.
At least 29 people have been injured in an explosion which rocked Manhattan. Here's what we know so far.