A woman was killed and her husband and daughter injured in a traffic collision at a barricade at a protest by French farmers against low wages and other grievances, authorities have said.

A car ploughed into straw bales that demonstrators had placed across a road, hitting the three people before it came to a stop against a tractor’s semi-trailer, prosecutor Olivier Mouysset said in a statement.

The fatal crash in southwest France represented a dramatic turn for the growing protest movement among French farmers for better remuneration and against what they consider to be excessive regulation, mounting costs and other problems.

The months of demonstrations have become increasingly vigorous in recent weeks, with traffic barricades, dumps of foul-smelling agricultural waste outside government offices and other protests. Farmers have also been turning road signs upside down to protest against what they argue are nonsensical agricultural policies.

France is one of Europe’s agricultural powerhouses, with powerful farming lobbies but also deep discontent among farmers who say they struggle to make ends meet despite working long hours to feed the country and boost its exports with their produce.

French president Emmanuel Macron’s government has been working to assuage farmers’ concerns before their anger blows up into a wider movement, like the yellow vest protests against economic injustice in 2019 that dented Mr Macron’s popularity and saw frequent violence between protesters and riot police.

Prime minister Gabriel Attal, newly installed by Mr Macron in a government reshuffle this month, posted on social media on Tuesday that “being a farmer means working without respite. It’s working for us, for the French. We are and will remain at their side”.

The woman hit and killed by a car in the Ariege region of southwestern France was a farmer, Mr Attal said.

“All our farmers are in mourning. Our nation is shocked,” he added.

Mr Macron, in a social media post, described the accident as a tragedy that “upsets us all” and said he had ordered his government to find ”concrete solutions” to the difficulties farmers were highlighting.

The car was carrying three people when it hit the barricade of straw bales in the Ariege town of Pamiers, the prosecutor said in his statement.

The woman killed in the pre-dawn collision was in her 30s, the statement said. Her husband, aged in his 40s, was seriously injured and hospitalised and their 14-year-old daughter was in a “worrying” condition, requiring her to be helicoptered for hospital treatment, the prosecutor said without giving more details.

The statement said the collision did not appear to be intentional. Police detained the three occupants of the car for questioning.