Over 10,000 birds -mostly migratory - have been found dead near Rajashtan's Sambhar Lake, the country's largest inland saltwater lake near Jaipur, since Monday.
The samples of the dead birds have led the forest department to believe the cause of death may be avian botulism, which occurs when birds feed on toxic substances.
A 70-member disaster management team is at Sambhar Lake, a key wintering area for tens of thousands of migratory birds, to dispose the carcasses so that botulism does not spread to other birds.
Also, a dozen teams from the Animal Husbandry Department are closely monitoring the situation.
Initially, it was suspected that the birds died due to avian flu but the report from a laboratory in Bhopal has ruled this out.
On Wednesday, Rajasthan Chief Minister Ashok Gehlot said the death of birds near the lake was worrying and protecting the flora and fauna remains one of the priorities of his government.
The strange episode has left villagers and people of the forest department baffled for the lack of a sensible explanation.
On Monday, 716 carcasses were taken out. The next day, 1,622 carcasses were fished out, followed by 1,922, 540, 3,265 on Wednesday, Thursday and Friday, respectively.
The number escalated on Friday despite several teams operating in and around the lake to analyse the reasons behind the mass deaths.
On Friday, the High Court questioned the state government for the reasons behind the death of these birds and has fixed November 22 as the next date of hearing.
Meanwhile, Forest Minister Sukhram Vishnoi, who was at the spot, said that around 150 people, including members from the municipal corporation and SDRF, were combing the lake.
"It has been confirmed that it is not bird flu which is killing birds. However, we are awaiting reports. Such an incident has been reported for the first time in India," he said.
Earlier this week, thousands of birds, including Northern Shoveler, Ruddy Shelduck, Plovers, Avocets, were found dead in the 5-7 km area around Sambhar Lake. Hundreds of migratory birds visit the Sambhar Lake at the onset of winter.