ROSEDALE, Md. (WJZ) — We are learning more about the preliminary report into the cause of the train derailment and explosion in Baltimore County.

Derek Valcourt takes a closer look at the findings.

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When a CSX freight train collided with a Mack truck in Rosedale May 28, the ensuing explosion could be felt for miles.

Now the NTSB’s preliminary report on that accident confirms four of the 47 train cars did contain hazardous materials, including sodium chlorate.

Investigators say the accident caused the first 15 cars to derail, releasing that hazardous chemical out of car seven and releasing terephthalic acid out of cars nine through twelve.

A fire then caused the subsequent explosion that damaged nearby homes and businesses, including the Plumbers and Steamfitters Apprentice Training School.

“I come running down. The closer I got to the office, the worse it was,” said Wayne Adkins.

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“They’re so lucky that nobody was in here,” said Jay Lancaster.

As investigators look at what went wrong, some of their attention has turned to the signs at the crossing, along with the standard railroad cross buck signs.

Investigators say the two stop signs there were non-standard–both of them faded yellow and displaced from their original mountings. One of them was even hanging upside down.

“And it was perpendicular to the road like a sign should be, it was turned at an angle away from the road,” said Robert Sumwalt, NTSB.

NTSB board member Robert Sumwalt says maintenance of the crossing signs is the responsibility of CSX.

“Nevertheless, the driver had come in and out of that area many times at day and certainly it was known to him that there was a railroad crossing there,” he said.

A full, complete investigation into the crash could take months.

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The driver of the truck, John Alban Jr., has been released from the hospital. NTSB investigators say they are still questioning him about what happened that day.