LEIPZIG, Germany — A bus carrying a tour group of 46 seniors and two drivers on a main north-south artery in Germany crashed on Monday into a tractor-trailer and burst into flames, killing at least 18 people, the Bavarian police said.

The crash occurred around 7 a.m. in stop-and-go traffic caused by construction along the A9 highway near Stammbach, in the southeastern state of Bavaria, the police said. At least 30 people were wounded, the police said, and two of them were reportedly in serious condition.

“It is now clear that all 18 missing bus passengers lost their life in the accident,” the regional police of Upper Franconia, in Bavaria, said on Twitter. Forensic specialists have been called in to help recover and identify the bodies.