SEATTLE – A 21-year-old man told police he shot and killed a passenger he didn’t know on a Metro Transit bus in Renton this week because he thought the man was going to threaten him, an investigator wrote in court documents filed Thursday.

Faisal Adan waived a court appearance and a judge set bail at $5 million, said Dan Donohoe, a spokesman for the King County Prosecutor’s Office.

It was not immediately clear if he had obtained a lawyer. He was due to face another court hearing Friday.

According to a probable cause statement filed by a detective, a witness reported sitting between Adan and the victim in the back of the Route 169 bus headed toward the Renton Transit Center on Tuesday afternoon. The witness said the two were speaking in a foreign language, but that the tone “did not suggest any issues or tension.”

Suddenly, the suspect pulled a gun out of his sweatshirt and repeatedly shot the other man, the witness reported. The gunman walked to the front of the bus, pointed the gun at the driver and demanded the bus stop, the witness reported. The gunman exited but was soon tracked down by Renton police.

The man who was shot died Thursday morning, the King County Sheriff’s Office said.

During a post-arrest interview with detectives, Adan “admitted that he shot the victim because he thought that the victim was going to threaten him,” the probable cause document statement said.

The documents also said that Adan, who has a scar from a gunshot wound in his abdomen, “stated that he was not going to be a victim again.”

Adan recently served a one-year sentence for joining two other young men in robbing a man of his Kindle in 2013, court records show. One of the men was armed with a gun in that case, authorities said.

Prosecutors said charges could be filed Friday.