An armed man holding dozens of people hostage on a Rio de Janeiro bus and threatening to light the vehicle on fire was shot dead by a police sniper after a four-hour long standoff on Tuesday, Rio's state governor Wilson Witzel said. 

Brazilian military police reported that all hostages had been released unharmed. 

The man, who was armed with a knife and a gun, took the busload of 37 people hostage at around 5:30 a.m. local time on a 13-kilometer-long (8-mile-long) bridge linking Rio with the neighboring city of Niteroi. After a four hour-long standoff, TV images showed the man emerge from the bus, throw a backpack towards the police and then collapse as he attempted to re-enter the vehicle. Authorities reported that he was shot by a police sniper. 

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At least six hostages had been released prior to the gunman's arrest. The hostages later told authorities the man had poured gasoline in the bus and made threats to set the vehicle on fire, police said.

Officials reported that the man had identified himself as a policeman, but they were unable to confirm this information. Local media reported that the weapon the attacker was brandishing was in reality a fake plastic gun.

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 "He told us he didn't want our belongings, that he didn't want to hurt us, that he just wanted to go down in history," said Hans Moreno, a hostage who had been sitting at the back of the bus. A spokesperson for the traffic police told the same station that the hijacker had not made any particular demands and seemed to have "psychological problems."

President Jair Bolsonaro tweeted his congratulations to the Rio de Janeiro police. "The criminal was neutralized and no hostage was injured. Today, no family member of an innocent person will be in tears," wrote the far-right former federal congressman.

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Rio de Janeiro is the second-most populous city in Brazil with more than 6 million inhabitants. It is located on the southeastern coast of the country.

mc/rc (AP, AFP)

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