Cause of the accident still was under investigation Monday night, and no injuries were reported, said Mike Fortney, Union Pacific Railroad spokesman. Hours after the 4 p.m. accident, a puffy white cloud of argon gas could be seen leaking out of a tanker car. A puncture in another car caused a small amount of methanol to seep from the tanker, Fortney said. The argon leak was not considered dangerous.
Methanol is explosive, but the leak was considered minor.
The train also had three boxcars derail that were carrying ammonium nitrate, a common fertilizer. One of those cars rolled down a steep embankment toward the river before stopping on its side a few feet from the water. Emergency officials were not sure late Monday night if the boxcar had ruptured, Fortney said. Chuck Streamer, a hazardous materials specialist with the city of Walla Walla Fire Department, said the leak in the tank carrying 16,000 gallons of argon gas did not appear dangerous, but precautions were being taken anyway. A Union Pacific hazardous materials team was coming from Portland to assess the scene, as was with a team of state Department of Ecology hazardous materials specialists from Spokane, Streamer said.