The New Delhi bound super-fast Rajdhani Express, which started from the eastern town of Dibrugarh in Assam state, had just crossed a station near Chungajan, 270 kilometers (170 miles) east of state capital Gauhati when the bomb exploded, jolting passengers out of their sleep, the AP reports.
"A car near the luggage van took the whole impact of the blast before dawn Thursday. Five passengers were killed and four others wounded," Rabha said.
The remaining 31 passengers in the affected car were shifted to another car and the train later resumed its journey.
"We suspect the bomb was planted inside the train from early examinations, but we cannot conclude for sure just now," police Superintendent P. Saloi said.
The Rajdhani Express is a popular air-conditioned train connecting India's northeast with the capital. It can carry 900 passengers, but wasn't running at full capacity, Rabha said.
Several rebel groups are fighting for autonomy or independence in the region. The militants say India's national government exploits the northeast's rich natural resources while doing little for the area's indigenous people, most of whom are ethnically closer to nearby Myanmar and China than to the rest of India.
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