BORDEAUX, France (AFP) — French authorities have detained a 15-year-old youth suspected of starting a forest fire that killed two firefighters, a source close to the investigation told AFP on Thursday.

The two firefighters were in a truck that became trapped by flames from a forest fire they were battling near Bordeaux airport in western France on July 21.

The source said the teenager had been formally placed under investigation and held in juvenile detention.

The deaths, along with that of a volunteer firefighter battling another blaze in southeast France, angered French firefighter unions who say they do not have the proper resources to take on the many wildfires in the country this year.

Representatives of nine unions met Interior Minister Laurent Nunez on Thursday. They said the commitments he made were not enough and threatened industrial action in September.

With much of the country in the grip of a new heatwave, firefighters were again battling forest blazes across France on Thursday.