- Assam's new Chief Minister sworn in, takes oath in Assamese
- PM, Amit Shah, veteran leader LK Advani and many union ministers present
- BJP celebrating its first government in the North East
Here are the 10 latest developments in this story:
"A leader belonging to the tribal community, a leader dedicated to serving society will now be the Chief Minister of Assam," said PM Modi as the grand ceremony turned into a victory rally after Mr Sonowal and his ministers had taken oath.
The PM began and ended his speech in Assamese, thanking the people of Assam for voting BJP and promising that Mr Sonowal and his team will "transform Assam." The lakh-strong crowd chanted "Modi, Modi."
"There are 14 NDA Chief Ministers here, and we are ecstatic that there is a BJP Chief Minister now leading Assam," said Amit Shah in his speech, ending with "Bharat Mata ki Jai" as did Madhya Pradesh Chief Minister Shivraj Singh Chouhan, who spoke before him.
Mr Sonowal, who made his first speech as chief minister in Assamese, said, "Like you voted us to power with a thumping majority, I hope you'll support us through our term. Hindus, Muslims, Sikhs, Christians all will work towards a better Assam."
Mr Sonowal also took oath in Assamese, as did Himanta Biswa Sarma who was sworn in right after the chief minister.
Himanta Sarma - who crossed over from the Congress last year and is credited with adding much fire power to the BJP's campaign in this election - also doubled as master of ceremonies. He is expected to be Assam's finance minister.
Seated on the massive stage with the BJP's allies was Tarun Gogoi, who was chief minister of Assam for 15 years before being vanquished by the BJP last week. Mr Sonowal personally invited Mr Gogoi, 80, and also sought his blessings.
Veteran BJP leader LK Advani too attended the ceremony at the sprawling Khanapara rally ground in Guwahati. Among other leaders who attended were BJP allies Chandrababu Naidu, Ram Vilas Paswan and Parkash Singh Badal.
10 ministers took oath today apart from Mr Sonowal. There will be six ministers from the BJP and four from its pre-poll allies - two from the Asom Gana Parishad or AGP and two from the Bodoland People's Front (BPF).
The Assam win signals the BJP's return to winning ways after losing two major elections it contested in Delhi and Bihar last year. The BJP and alliance partners won 86 seats in the 126-member assembly.