A gunman wearing a gas mask filled a crowded New York subway car with thick black smoke from a canister and opened fire on morning rush-hour passengers, injuring more than 20, including 10 with gunshot wounds. A manhunt was under way on Tuesday after the shooter, described as a heavy-built Black male about 5ft 5in tall, wearing a green construction-type vest and hooded grey sweatshirt, fled the scene of the shooting. Officers were searching for a U-Haul truck with an Arizona license plate as of Tuesday afternoon, police told multiple media outlets, and the vehicle was later found. Injured passengers suffered from bullet wounds, smoke inhalation and the physical effects of panic. Nobody was reported to be in life-threatening condition. Joe Biden said on Tuesday afternoon: “We’re not letting up until we find the perpetrator” and thanked professional first responders and civilians who rushed to help their fellow travelers amid the panic. The US president spoke at an event in Iowa, as the New York mayor, Eric Adams, indicated the authorities were getting ready to share the identity of the gunman, who was still at large. On Tuesday morning, graphic photographs and clips posted on social media showed the traumatic scenes on the platform of 36th Street station in the Sunset Park neighbourhood of Brooklyn around 8.30am. Wounded passengers were seen lying as others administered tourniquets to staunch bleeding from their legs. Another phone image showed blood smeared inside the train carriage and out on to the platform, indicating where a rider had been dragged to safety. Footage captured passengers screaming as they scrambled to escape the shooter. Biden added that he and the first lady, Jill Biden, were “praying for all those touched by this trauma”. In a press conference, the New York city police commissioner, Keechant Sewell, described events that began shortly before 8.24am as an N train bound for Manhattan was travelling between the 59th and 36th Street stations. “An individual on that train donned what appeared to be a gas mask,” Sewell said. “He then took a canister out of his bag and opened it.” Sewell continued: “The train at that time began to fill with smoke. He then opened fire, striking multiple people on the subway and in the platform.” The commissioner said there was no known motive for the actions of the suspect. She sought to calm nerves among New Yorkers by saying the shooting was not being investigated as an act of terrorism, but later said she was “not ruling out anything”. Agents of the joint terrorism taskforce were at the scene, along with FBI and NYPD officers. Biden and the US attorney general, Merrick Garland, were briefed. The attack brought fear and chaos back to New York City. Witnesses said they heard so many shots they lost count. Others said the shooting sounded like fireworks or popping, causing confusion among passengers. Yav Montano, who was present inside the carriage as the attack unfolded, shared with CNN a 10-second video he captured as the train drew into the 36th Street station. People could be heard groaning and coughing and were seen covering their faces against thick smoke. Montano said a smoke grenade was let off about two minutes before the train reached the station. Noise erupted and he crouched to the floor in an attempt to shield himself. “I didn’t realise it was shooting to start with,” Montano said. “It sounded like fire crackers, or a bunch of scattered popping.” Montano estimated there were 40 to 50 passengers in the carriage. “There were some people whose pants were covered with blood,” he said, adding that there was blood on the floor. “All I saw was people trampling each other, trampling over each other, trying to get into the door which was locked and just a lot of panic.” The passenger said the train slowed to a halt shortly before it reached the 36th Street station. “That’s when the chaos happened. Thank goodness the train moved, because I don’t know what would have happened otherwise,” he said. Other graphic footage was recorded as the N train pulled in. As its doors opened smoke poured out followed by passengers, some screaming, others stumbling and falling to the platform. Phone images showed blood on the floor of the car. Later, there were reports that the gun had been found, a Glock pistol, which had jammed during the incident, also amid reports that the investigation was hampered by station security cameras not functioning. New York has been grappling with high-profile violent incidents on the subway, prompting the relatively new mayor, Adams, to beef up police patrols. Adams, who is self-isolating with Covid, said: “We will not allow New Yorkers to be terrorised, even by a single individual.” Kathy Hochul, the governor of New York, told reporters: “We say ‘No more’. No more mass shootings, no more disrupting lives, creating heartbreak for people. We are sick and tired reading headlines about crimes. It has to stop.” As the manhunt got under way, officers fanned out across the Sunset Park neighbourhood, a largely working-class area with large Hispanic and Chinese-origin populations. Schools were put on lockdown. New York fire officers said they were looking at up to four undetonated devices, but later confirmed there were no active explosive devices. At least 21 injured passengers were treated at NYU Langone hospital –Brooklyn, said a facility spokesperson, Lacy Scarmana. As of Tuesday afternoon, 10 had been discharged, with 11 remaining in relatively good condition, Scarmana said. A statement from New York-Presbyterian hospital said staff there treated three other people injured in the morning’s subway shooting. All were in relatively good medical condition as of Tuesday afternoon, a hospital spokesperson, Tony Chau, said in a statement. Fire officials said they had taken a total of 17 victims from the scene of the subway attack to multiple local hospitals, including those with gunshot wounds. Five were reported to be in critical but stable condition. Others arrived at those facilities on their own.