Paris  - French President Nicolas Sarkozy will visit later Tuesday the south-eastern town of Allinges to pay tribute to seven schoolchildren who were killed when a regional train slammed into their bus on Monday, his office said.

Twenty-five people were injured in the collision, the deadliest accident involving a schoolbus in France in more than 25 years. Three of the injured were said to be in critical condition.

The accident occurred at a level crossing near Mesinges, on the railway line between Annemasse and Thonon-les-Bains, in the region of Upper Savoy. Two investigations have been opened to find its cause.

France Info radio reported Tuesday that initial findings, based on witness accounts, suggest that the driver may have ignored signals and tried to make it across the tracks as the crossing gates were descending.

The bus was transporting 50 students between 11 and 13 years of age and six adults on a school trip to the picturesque medieval village of Yvoire, on Lake Geneva near Thonon-les-Bains.

The students were all from a school in Margencel, where fellow students and teachers were said to be in a state of shock. Psychological counseling was being offered to the students. (dpa)