HYDERABAD, India — Four Spanish nationals and their Indian driver were killed Saturday in a collision between their bus and a trailer truck on a highway in southern India, police said.

Seven other Spanish nationals were injured in the accident at a road bend and were hospitalized, said police officer Hari Prasad.

Prasad said the Spanish nationals were volunteers with the Rural Development Trust, a nongovernmental organization that assists poor villagers in Anantpur district, 560 kilometers (350 miles) south of Hyderabad, the capital of Andhra Pradesh state.

Further details were not immediately available.

The Rural Development Trust is a landmark for thousands of Spanish tourists and volunteers visiting India. The organization, known in Spain as the Vicente Ferrer’s Foundation, was established in 1969.

Police figures show India has the world’s deadliest roads, with more than 110,000 people killed each year in crashes. Driver fatigue and negligence, low-quality roads and poor vehicle maintenance are frequent causes of accidents.