Haze, powder from discharged fire extinguisher at Downtown Crossing.

Even normally jaded Red Line passengers were rattled after their train pulled into Downtown Crossing shortly after 9 p.m. yesterday and a fire alarm went off, the air and platform filled with haze and powder and somebody began screaming obscenities through the train PA system.

"We had four or five juveniles discharge a fire extinguisher and then flee the scene," Transit Police Superintendent Richard Sullivan reports. "No one was injured. Service was delayed approximately five minutes area search proved negative. We will conduct a follow up investigation."

A friend of one of the passengers on the train forwarded the above photo of the powder-filled platform before Boston firefighters arrived for their own investigation.

See Full Page