(CNN) -- At least 22 people died and another 31 were injured in eastern Peru when a bus plunged off a mountain road, news reports said Monday.
The state-run Andina news agency had reported 19 dead Sunday, just hours after the early morning accident in the Andes Mountains.
The bus, which carried foreign tourists, was only eight minutes away from arriving at the town of Quichuas on Sunday morning, Andina news said. It was traveling from the town of Ayacucho to Peru's capital, Lima, news reports said.
Most of the passengers were students and staff from the University of Huamanga, said Radio Programas del Peru, known as RPP. Three students and a professor were among those killed, RPP said.
Two of the dead were Colombians, RPP said.
The vehicle came to rest more than 100 meters (328 feet) below the road, in the rocky Mantaro River, Andina said.
Officials were still investigating the cause of the accident Monday. The bus was operated by the Molina Union transportation company, Andina said.