A "strong burning smell" was reported in the lead railcar at 30th Street Station in Philadelphia about an hour before a SEPTA Regional Rail train with about 325 passengers caught fire at Crum Lynne Station in Ridley Park last month, federal officials said.

The National Transportation Safety Board released a preliminary report on Wednesday about after a SEPTA Regional Rail train traveling from West Trenton, New Jersey, to Newark, Delaware, forced hundreds to evacuate. A SEPTA spokesperson declined to comment on the NTSB report due to the ongoing investigation.

SEPTA is estimating damages of the equipment to cost $10 million, according to the NTSB. A four-person crew was on the train when it caught fire.

Before the fire and reported burning smell, the SEPTA train appeared to show that it wasn't operating efficiently, according to the NTSB. 

At about 3:50 p.m. on the day of the fire, an engineer contacted SEPTA's Regional Rail Operations Control Center (RROCC) in Philadelphia while the train was at Bethayres Station in Montgomery County. The engineer told RROCC that the train was "sluggish and not getting up to speed, and that a fault light on the train was on," the NTSB said. 

A dispatcher at the RROCC then called for the train to undergo maintenance at Roberts Yard, which is a SEPTA railroad facility just south of Wayne Junction. 

After inspecting the train, the NTSB said the mechanical maintenance team told a SEPTA superintendent of train operations at the RROCC that three railcars were "bad" and causing the train to accelerate slowly. But the train continued to operate. 

The train consisted of six railcars, according to the NTSB. Crews working on the railcar changed at Suburban Station at about 4:55 p.m.

At about 5:07 p.m. while the train was at 30th Street Station, the NTSB said an engineer on the train reported to SEPTA's chief dispatcher at the RROCC that there was a "strong burning smell in the lead railcar," according to the NTSB. Despite the burning smell, the train continued to move out of Philly and down the Wilmington/Newark Line toward Delaware County. 

The NTSB said an engineer noticed a haze behind the lead railcar as the train arrived at Crum Lynne Station at about 5:48 p.m.,  right before the fire. After stopping at the station, the train started to leave and the engineer saw smoke behind the lead railcar, according to the NTSB. The train then stopped about 650 feet south of Crum Lynne Station. 

According to the NTSB, the engineer onboard the train inspected it just before 6 p.m. and discovered the lead railcar was on fire. The train, with about 325 passengers onboard, was evacuated. Nobody was injured in the blaze. The fire was placed under control at about 8:09 p.m., the NTSB said. 

The NTSB was on the scene the night of the fire and examined railroad equipment and track conditions, reviewed data from surveillance cameras, completed interviews and more.

The NTSB said the investigation into the fire is ongoing. The future of the investigation will focus on identifying the source of the fire; inspecting the electrical wiring in railcars; evaluating SEPTA's railcar inspection, maintenance and repair process; and examining the RROCC's response to en route train failures. 

The Federal Railroad Administration, SEPTA, Amtrak, Brotherhood of Locomotive Engineers and Trainmen and the International Association of Sheet Metal, Air, Rail and Transportation Workers were all involved in the investigation.