PARIS — A rail joint that worked loose from a track switching point appears to have caused France’s worst train accident in years, an official with the national rail company said Saturday.

The crowded intercity train, leaving Paris at rush hour before a holiday weekend for the city of Limoges, jumped the tracks 20 miles south at Brétigny-sur-Orge station. The seven-car train split into two, with some cars riding up the station platform and flipping over.

Six people died, two were in critical condition and seven more were in serious condition, officials said; 21 others were still in the hospital. More than 190 people were treated at the site for lesser injuries.

Officials said the death toll might increase as the wreckage was removed because some people might be under the overturned cars.