An explosion that occurred on Saturday in Manhattan, New York, US, has injured nearly 29 people, New York Governor Andrew M. Cuomo has said.

The bomb, which comprised a pressure cooker filled with explosives and shrapnel, was similar to the devices used at the 2013 Boston marathon, BBC reported.

A similar unexploded pressure-cooker device, also filled with shrapnel, was discovered a few blocks away from the site of the explosion.

"We’re going to be very careful and patient to get to the full truth here."

The Associated Press quoted New York City Mayor Bill de Blasio as saying: “We’re going to be very careful and patient to get to the full truth here.

“We have more work to do to be able to say what kind of motivation was behind this. Was it a political motivation? A personal motivation? What was it? We do not know that yet.”

Following the explosion, Cuomo has called on the State Police and National Guard to deploy an additional 1,000 uniformed officers across the state.

The Manhattan blast was followed by another explosion at Elizabeth train station in New Jersey on Monday, the Associated Press reported citing the city's mayor Chris Bollwage.

The explosion occurred while a bomb squad was attempting to detonate a suspected device at the station.

No injuries were reported as a result of the explosion, according to The Guardian.

The FBI is carrying out an investigation and working to detonate four other devices found at the station.