UP CM said 'it does not matter who built it and for what reason; it was built by blood and sweat of Indian labourers'.
The double-decker bus belonged to Awadh Depot and was going to New Delhi from Lucknow.
The migrants were ferried to their villages in sanitised buses arranged by the Jharkhand government to take them home after preliminary medical screening at the station, officials said.
The MeT department has warned of rain or thunderstorm at isolated places in the state in the next two days.
PM Modi, BJP president J P Nadda, Congress leader Rahul Gandhi and Delhi Chief Minister Arvind Kejriwal have all expressed grief over the incident.
This was the third consecutive day that COVID-19 cases in the country have increased by more than 26,000.
Around 90-100 people received burn injuries, and the condition of some of them was serious.