BOSTON -- Dozens of passengers were treated for smoke inhalation after an electrical fire broke out on the MBTA Red Line Thursday night, officials said.

At least 17 passengers, between the ages of 3 months and 50, were taken to area hospitals.

The fire forced the MBTA to shut down much of its underground system.

The electrical fire broke out on the tracks north of the Downtown Crossing station around 10 p.m. Boston firefighters struck a third alarm for the fire.

Passengers on a train that was passing through the station said a big white cloud of smoke came right at them, choking them and burning their eyes.

Several hundred passengers were then evacuated from the train and station. The injured were seen being taken out on stretchers and put into waiting ambulances.

None of the injuries appeared life-threatening.

One passenger said the train they were on had pulled into the station and when the doors opened, the operator quickly closed them because of the intense smoke in the station.

Smoke from the fire disrupted service on several subway lines, MBTA spokesman Joe Pesatauro said.

Buses replaced Red Line service from Broadway to Harvard.

Buses were in service on the Orange Line from Back Bay to North Station and on the Green Line from Arlington to North Station.