Dutch police fired shots at tractor-riding farmers who were protesting against plans to cut nitrogen emissions on Tuesday evening in northern Netherlands.

Police said they were responding to a "threatening situation" when the farmers, who were attempting to push past a blockade to get onto a highway in the province of Friesland, started to drive their tractors into officers and their vehicles.

According to the Friesland police, their shots hit a tractor, but no one was injured. Three suspects were arrested. The Rijksrecherche, the Dutch government's internal investigator, said it would look into the events given police had discharged their weapons.

A spokesperson for the Friesland police did not respond to inquiries, but said a statement would be released later Wednesday.

Dutch farmers have this week been protesting government plans that could require farmers to use less fertilizer and reduce their livestock numbers, which could force some farms to shut.

The Dutch government wants to reduce emissions of nitrogen oxide and ammonia, which are produced by livestock, by 2030. Cuts could reach 70 percent in some areas, under the plans.

In response, Dutch farmers have blocked supermarkets, distributions centers and roads in protests this week. Wednesday morning, they are expected to demonstrate at the Groningen Airport Elde, according to Dutch media.