At least 14 people died, two of them children, in a collision between a truck and a bus near the city of Zainsk in Russia's Tatarstan region, authorities say.
A spokesperson for the local police department said the accident occurred shortly after midnight on July 2.
The bus was traveling from Samara on the Volga River to Izhevsk, around 900 kilometers east of Moscow, when the accident happened, the Investigative Committee, which probes accidents and disasters, said on July 2.
The committee said it was possible that the bus driver was blinded by headlights.
The regional Interior Ministry said the bus rolled over and caught on fire following the collision with the truck.
Earlier on July 12, a spokesman for Tatarstan's Health Ministry was quoted as saying at least 15 people had been injured, four in serious condition.
A criminal investigation into the accident has been opened, the ministry said, adding that it would be arresting both drivers.
The president of Tatarstan, Rustam Minnikhanov, has declared July 2 a day of mourning for the victims, his office announced.
Tatarstan's prime minister, Aleksey Pesoshin, traveled from the capital, Kazan, to the site of the crash.
In other deadly road accidents, four people died early on July 2 after a car hit a tree near Nizhny Novgorod, east of Moscow, and two teenagers were killed late on July 1 when a truck plowed into a bus stop in Bryansk in western Russia.
Russia ranks among the world's worst countries for road deaths, mainly due to drunk driving, poor roads, and traffic violations.
Last year, more than 20,000 people died in road accidents, a 12 percent drop compared to 2015.
With additional reporting by TASS, AFP, and Vesti Kamaza