An attack on a TriMet bus is raising new questions about security.

Witnesses told police that a young man approached two passengers on a TriMet bus Wednesday, threatened them with a knife and brass knuckles and began to fight with them.

Andres Napolean-Marcos, 20, identified himself as a gang member before starting to fight, police said.

The victims struggled with the suspect for control of the knife as the bus driver activated the alarm to notify police and ordered everyone off the bus.

Everything was caught on tape, with a surveillance camera mounted inside the bus.

Police photo

Suspect Andres Napolean-Marcos

The fight continued and eventually spilled out onto the street, where officers found the victims and suspect and arrested Marcos.

The incident happened Wednesday morning near Northeast Martin Luther King Jr. Boulevard and Northeast Roselawn Street.

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Napolean-Marcos was lodged in the Justice Center jail on charges of attempted assault, assault, unlawful use of a weapon and menacing

 Video: Watch KGW report on TriMet attack

This is the second attack on a TriMet bus this month.

 More: TriMet bus driver attacked by passenger

A passenger on a bus hit a driver in the head after she confronted him for failing to pay. That driver was not seriously injured, but quite shaken.