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Service on one of Boston’s subway lines was interrupted on Thursday morning when what firefighters described as a small fire was reported underneath a train car and they had to manually carry water up to an elevated platform to fight it because the station’s firefighting standpipes weren’t working, authorities said.

The operator of a northbound train at the Red Line’s Charles/MGH station saw smoke coming from the undercarriage area just before 6 a.m., a spokesperson for the MBTA said in an email.

Passengers got off the train and evacuated the station, and there were no injuries reported.

Train service was replaced by shuttle buses between the Red Line’s Broadway and Kendall Square stations. Shuttle buses were drawn from bus routes busy with commuters, triggering delays of up to 25 minutes on several routes, according to MBTA service alerts.

Normal Red Line service resumed by 8:40 a.m., according to the T’s official Twitter account.

Banker & Tradesman staff writer James Sanna contributed to this report.