Explosion rocks busy New York city neighbourhood; injures 25

The explosion - which came hours after a pipe bomb went off in a garbage can in New Jersey - occurred in the Chelsea neighborhood at 23rd St. and 6th Avenue, a busy residential and commercial area frequented by tourists and city residents, around 8:30 pm (local time) yesterday.

The Fire Department of New York tweeted that 25 people have been injured and have been taken to hospitals in the area.

Authorities said "none appear to be life-threatening at this time". Personnel from the New York Police Department, FBI and counter-terrorism agencies are on the scene where restaurants and shops have been evacuated and subways in the area have been shut down. Mayor Bill de Blasio was also headed to the scene.

Assistant Commissioner for Communication and Public Information at the New York City Police Department J Peter Donald tweeted that authorities are responding to a report of an explosion at 23rd St. and 6th Avenue in Manhattan.

"We will update you w/more when we have it," Donald said. The explosion came hours after another explosion went off in a garbage can in a New Jersey beach town yesterday morning. Three pipe-bomb-type devices wired together were found near the boardwalk in Seaside Park, according to CNN. No injuries were reported and a four-block area was evacuated for most of the day, authorities said.

Security is already tight in the city as nearly 190 world leaders, including President Barack Obama, will arrive in the city for the about week-long high-level annual UN General Assembly session, beginning tomorrow.

Obama has been appraised of the explosion in New York City, a White House official said. "The president has been apprised of the explosion in New York City, the cause of which remains under investigation. The president will be updated as additional information becomes available," a White House official said.