Fifteen people were killed Sunday when a minibus collided with two trucks in Russia's southern Ulyanovsk region, news agencies reported.

According to witnesses quoted by news agencies, a truck veered off the road when it collided with a minibus travelling in the opposite direction near the village of Nikolayevka.

At the time of the accident, the minibus was also hit from behind by another truck. According to footage broadcast by Russian television channel Ren TV, the minibus was almost completely flattened by the two trucks.

The accident left 15 dead, all Kazakh citizens, rescue services quoted by the Russian state agency RIA Novosti said.

Three other people -- two men and a woman -- were taken to hospital in a serious condition, Ulyanovsk regional governor Alexei Ruskikh wrote on Telegram.

Violations of road safety regulations are common in Russia, where several deadly bus accidents have occurred in recent years.

In January, five people were killed and 21 injured in a bus accident in the Riazan region, about 270 kilometres (170 miles) south of Moscow.

In December 2019, a bus with around 40 passengers on board plunged into a frozen river in the Zabaikalsk region of Siberia, killing 19 people and injuring 21.