A knife-wielding man dressed as the Joker went on a crazed rampage aboard a Tokyo commuter train Sunday, stabbing at least 17 people and starting a fire before finally being taken into custody.

The unidentified attacker brandished a knife and began slashing passengers aboard the crowded Keio train near the Kokuryo station while wearing the Batman villain’s costume, NHK News said in a report.

“I thought it was a Halloween stunt,” one witness told reporters. “Then I saw a man walking this way, slowly waving a long knife.”

He said the knife was covered in blood. 

Passengers scrambled to escape, some climbing through train windows and others fleeing to other cars, as smoke began to fill the train after the suspect poured a flammable liquid and set it on fire, the outlet said.

Police arrested the costumed man, but not before he wounded 17 commuters — at least one now in critical condition.

Authorities did not reveal a motive for the attack, but local outlets reported that the attacker “wanted to kill people so he could be sentenced to death.”

The incident marked the second stabbing aboard a train in the Japanese capital.

In August, one day before closing ceremonies at the Tokyo Olympic games, a 36-year-old man also stabbed 10 passengers aboard another commuter train.

In that case, the suspect told police he wanted to attack women who looked happy.

With Post wires