At least six people were killed and 15 people injured after an incident on the west side of lower Manhattan in New York City.

Police are investigating reports of gunfire and a vehicle striking people near the West Side Highway and Chambers Street.

Officials told the New York Times and NY1 at least six people had been killed in the incident. A law enforcement source told Reuters that the incident is being treated as terror-related.

New York Police Department said one person has been taken into custody.

Police responded to reports of gunfire near Stuyvesant High School at around 3 pm on Tuesday.

Fox and ABC also reported that several people had been hit by a pick-up truck  that rammed into a bike lane.

New York Mayor Bill de Blasio was briefed on the incident and later appeared on the scene.

President Donald Trump was also briefed on the incident, and New York Governor Andrew Cuomo also announced he would visit the site.

John Williams, a 22-year-old Brooklyn College student, said he arrived on the scene near Stuyvesant High School just after the crash had taken place. He told HuffPost he heard at least five “very fast” gunshots.

“I heard people yelling, ‘He’s got a got! He’s got a gun!’” said Williams.

Williams said he saw a man being arrested and another man, who “looked like had been shot,” laying on the ground nearby. He described the crashed vehicle as a white pick-up truck with a Home Depot logo.

“The front was mashed in,” William said. “And there was smoke coming out of it.”

An eyewitness told ABC Channel 7 that he saw a white drive south down the bike path alongside the West Side Highway at full speed and hit several people.

The witness, a man identified by the name “Eugene”, said bodies were lying outside the high school, one of the city’s elite public schools.

He also reported hearing about nine or 10 shots, but was not sure where they came from.

The West Side Highway runs on the western edge of Manhattan, alongside the Hudson River.