"At least one person was taken to hospital, but the exact number of injured and the condition of the wounded is not yet known," spokesman for the local Groningen crisis team, Cyriel Hamstra said.
Only about 20 people had been on the train at the time of the crash, he added.
The tanker truck was leaving a farm in the rural area of Winsum and "was probably driving over an unguarded railway crossing when it was hit by an oncoming train," Groningen police said on their Twitter account.
Ambulances and a helicopter were already at the site of the crash which happened around midday (local time).
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"Most of the injured are only slightly hurt," Groningen police spokesman Ernest Zinsmeyer told the NOS public broadcaster.
Television images from the NOS public broadcaster showed the first few carriages of the train had derailed, and it was partly tipped onto its side in a field.
"There is a large presence" of rescue workers "to help the wounded", Hamstra said.
Train links to the region had been stopped for the time being, and all the passengers were evacuated.
The crash happened at a place where the railway line passes through several fields following the path of a canal, according to the television images.