Preliminary damage estimates for the fiery Casselton, North Dakota train derailment have been released by the National Transportation Board.

Now, U.S. lawmakers are calling for new freight and rail tank car safety standards.

Federal officials estimate the damage to be over $6 M. More than 400,000 gallons of oil was lost in the incident.

According to the report, a westbound train carrying soybeans derailed, causing a grain car to fall on the tracks. An eastbound train then derailed after crashing into the grain car.

About 14,000 people voluntarily evacuated the town, and nobody was hurt as a result of the massive explosions on December 30.

Now, U.S. Senator Amy Klobuchar is calling for discussion to help improve the safety of towns and those living along rail routes while still maintaining the industry.

In a letter, Klobuchar urges the Senate Committee on Commerce, Science, and Transportation to hold oversight hearings on the Federal Railroad Administration and the Pipeline and Hazardous Materials Safety Administration.

"Our 21st century economy demands a 21st century transportation network that includes rail safety investments that protect communities from derailments involving hazardous materials," Klobuchar said.

In the statement, Klobuchar said only roughly 14,000 of the 92,000 tank cars that carry hazardous materials meet the latest safety standards.

The Senator says the hearing should carefully consider three other recent train derailment incidents in Maine, Quebec and, the derailment in Two Harbors.

Officials are still investigating the incident in Two Harbors in which 100 cars carrying iron ore derailed.

Four CN railroad crew members were involved, two were hospitalized.