US President Donald Trump called Wednesday for Sayfullo Saipov, the man charged with carrying out a New York City truck rampage that killed eight people, to be put to death. "NYC terrorist was happy as he asked to hang ISIS flag in his hospital room. He killed 8 people, badly injured 12. SHOULD GET DEATH PENALTY!" Trump wrote on Twitter. The president had earlier said he would consider sending Saipov to Guantanamo Bay, the US military detention center in Cuba that has been used to indefinitely hold suspected foreign militants, a practice that has drawn repeated criticism from rights groups. Trump had also called for eliminating the 1990s visa lottery program that Saipov, an Uzbek immigrant, used to come to the US in 2010. Federal authorities said in a criminal complaint bringing terrorism charges against Saipov that he was inspired by ISIS’ online videos and plotted his attack for two months, renting a truck ahead of time to practice turning it. After his train of terror, Saipov, 29, was halted by a police bullet. He asked to display ISIS’ flag in his hospital room, saying "he felt good about what he had done," authorities said. Brought to court in a wheelchair, Saipov was held without bail on charges that could bring the death penalty. Separately, the FBI was questioning people who might have information about his actions before the attack, including a second Uzbek man. The charges against Saipov, came just a day after the attack near the World Trade Center killed five people from Argentina, one from Belgium and two Americans. Twelve people were injured. Investigators in multiple states raced to retrace Saipovs steps and understand his motivations. Saipov had a cellphone loaded with the groups propaganda, an FBI agent said in the criminal complaint. He sped down a bike path on a riverfront esplanade in a rented truck for nearly a mile Tuesday, running down cyclists and pedestrians, before crashing into a school bus, authorities said. He was shot after he jumped out of the vehicle brandishing two air guns, they said. Knives were found in a bag he was carrying.