Indian police say the Khorasan unit of IS triggered a low intensity train blast in the country, marking its debut here. In February, the terrorists killed over 90 people in an attack on a Sufi shrine in Pakistan.

After 12 hours of high intensity firing, Indian police killed a suspected terrorist of the Khorasan module of IS, also known as ISIS, in a case related to a low intensity train blast on Tuesday, making it the first Khorasan attack in India.

"The slain terror suspect belongs to the Khorasan module of the ISIS and was an active member. But, whether he has been indoctrinated or not is a matter of investigation," said Anti-Terrorist Squad chief Aseem Arun.

Police officials are looking for two more suspects. The encounter took place in Lucknow, the capital of India's most populous state, Uttar Pradesh, which is in the process of electing a new government.

After the encounter in the thickly-populated Thakurganj area, police recovered explosive materials, pistols and several articles.

Since Tuesday afternoon, police were trying to catch the suspect alive. Chilli bombs were used to draw him out, but nothing worked, Arun said. The intelligence unit suspected these terrorists were planning a major attack in the state which has more than 200 million inhabitants.