The mishap occurred on the Badrinath national highway about 15-km ahead of the high altitude pilgrimage centre in Uttarakhand's Chamoli district yesterday evening, police said.
The bus, coming from Delhi, was carrying pilgrims from the UK to Badrinath when boulders rolling down a hill in Lambagar fell over the bus killing 60-year-old Shobhna Ben Patel from London on the spot and injuring four others, they said.
There were 21 pilgrims in the bus heading for Badrinath after paying obeisance at Kedarnath, another important pilgrimage centre in the hill state.
The injured have been admitted to Joshimath government hospital, they added.