A derailed train caught on fire in the United States on Wednesday causing a bridge to partially collapse over Tempe Town Lake in the state of Arizona, according to local media reports.

“A spokesperson with Tempe Fire Department says the incident involves a Union Pacific train that derailed, causing a partial bridge collapse over Tempe Town Lake,” local ABC15 reported. “Flames could be seen running across the bridge and in an area of Tempe Beach Park.”

The cause of the derailment is currently unknown, and no injuries were reported, according to the report.

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ABC15 estimated that about 90 firefighters were called to the scene of the “second-alarm hazardous materials response.”

The report also said that authorities are working “to determine what was in each of the train cars and whether there could be further hazards.”

However, a CBS news affiliate KPHO-TV reported that “a burning train car was reportedly carrying lumber, some of which went into the lake below the train bridge.”