(CNN) -- The body of the driver of one of two commuter trains that collided head-on in western Switzerland has been found in his crushed cab, Swiss police said Tuesday.
Twenty-five of the passengers needed hospital treatment after the crash Monday evening, police in the Vaud canton said in a news release, one fewer than had previously been stated.
Nine others were treated on the spot for minor injuries and 11 others were unharmed, police said.
The train driver who survived, age 54, was injured and is in hospital, Swiss Federal Railways spokesman Reto Schaerli told CNN.
The collision happened just outside the village of Granges-pres-Marnand, about 8 kilometers (5 miles) south of Payerne.
Authorities are trying to determine what caused the crash.
The latest details were given in a news conference Tuesday by the Vaud police and senior Swiss railways officials.
At this early stage, police believe that the train driver who survived was supposed to have waited at the train station in Granges-pres-Marnand until the other train had passed, but did not, Schaerli said. It is not yet clear whether there were any technical or safety failures, he said.
Police said the surviving driver had stopped his train at the station to allow passengers to board and disembark. Moments after he set off again, the two trains slammed into each other. The driver had time to apply the emergency brake before the impact, police said.
The trains were traveling between Payerne and Lausanne, a city on the shores of Lake Geneva, when they collided. No foreigners were on the trains, according to police.
Firefighters used heavy machinery to separate the crumpled trains and access the cab where the 24-year-old driver's body was found early Tuesday, police said.
The local government sent its condolences to the driver's family.
A Swiss Federal Railways statement said "this is a very sad day and we regret the loss of one of our colleagues as well as those who were injured."
The line between Lausanne and Payerne will remain closed Tuesday, police said.
CNN's Susannah Palk and Stefan Simons contributed to this report.