As the odour intensified at around 10 PM, the residents started coming out of their homes, an official from Thane city police control room said, adding that a few of them had to be rushed to the civil hospital.
Chief of Regional Disaster Management Cell, Thane Municipal Corporation (TMC), Santosh Kadam, who went to the site with firemen and police personnel, said that it was a case of burning of chemical waste at the dumping ground.
Meanwhile, Kadam said that the movement of traffic in the area was stopped due to heavy smoke from the site.
As many as 10 villages complained of the foul smell from the area, he added.