New Brighton, Pa. ? Federal investigators arrived at a smoldering scene Saturday to piece together how two dozen ethanol tanker cars derailed and several exploded on a southwestern Pennsylvania bridge.

No one was injured late Friday when 23 cars from the train’s midsection derailed and nine caught fire on the half-mile long rail bridge over the Beaver River in New Brighton, about 25 miles northwest of Pittsburgh.

As tanker cars continued to burn late Saturday, National Transportation Safety Board officials said they would gather maintenance records and interview witnesses, including crew members of the Norfolk Southern train.

“I actually felt the explosion at my house. It was like lightning struck in the front yard,” said New Brighton borough manager Larry Morley, who lives several blocks away and saw a fireball rise in the air. Ethanol is also known as grain alcohol.

The train – 89 tanker cars pulled by three locomotives – was traveling from Chicago to New Jersey when it derailed.

NTSB investigators removed data recorders, similar to black boxes found on airliners, from three locomotives as well as a section of track that was broken in two, officials said.

Robert Sumwalt, vice chairman of the safety board, said preliminary indications from the recorders showed that the train was traveling 36 to 39 mph when the middle tanker cars derailed. The speed limit is 45 miles per hour along the track.

Flames and smoke rise Saturday from a derailed Norfolk-Southern train in New Brighton, Pa. Twenty-three cars containing ethanol derailed, and nine caught fire on a bridge over the Beaver River late Friday.

Ten federal safety board experts were on the scene and will be investigating mechanical issues, human factors, track and engineering issues, and the emergency response to the crash, Sumwalt said. Officials expected to interview the train’s two-man crew, its engineer and a conductor today.

The crew, engineer and conductor also are expected to take toxicology tests, which are routine under federal guidelines in this type of accident.

“At this time, our investigation is just beginning,” Sumwalt said. “We want to collect information before we start making analytical statements.”

None of the cars on land was burning and the fire was not expected to spread beyond the derailed cars.

Officials with the state Department of Environmental Protection, Norfolk Southern and Beaver County were determining whether to let the fire burn itself out or extinguish it, Sumwalt said.

About 50 people who live nearby spent the night in a makeshift shelter at a local school because of concerns of possible explosions.

State officials were also monitoring the water and air quality, Sumwalt said. Downstream water users were notified of the incident as a precaution, DEP spokeswoman Betsy Mallison said.