The finding was reported at 7:07 a.m., VTA spokeswoman Jennie Loft said.
The train was stopped at the station. Passengers were taken off the train and put on busses to continue on to their destinations. All other trains continued operating, she said.
At about 8:25 a.m., the hazmat team determined the suspicious substance was detergent, Loft said.
The train that was temporarily stopped was expected to be released at about 9 a.m.