The first "Oxygen Express" train reached Indian capital New Delhi on Tuesday carrying about 70 tonnes of life-saving gas for overwhelmed hospitals as the coronavirus outbreak sweeps the nation.
New Delhi is the most populous city in India, with about 30 million residents.
Hospitals have been turning away patients in need of life-saving treatment because of a lack of beds, oxygen and supplies.
Dr K Preetham, chief of medical administration at the Indian Spinal Injuries Centre in New Delhi, said the scarcity of oxygen was the main concern.
"For seven days, most of us haven't slept. Because of the scarcity, we are forced to put two patients on one cylinder and this is a time-consuming process because we don't have long tubes," he said.
As demand for oxygen soared in the country after an exponential surge in cases, the government turned to India's vast train network.
Converted rail carriages brought field hospitals full of doctors into the centre of hot spots and now "Oxygen Express" trains are speeding tonnes of liquid medical oxygen and oxygen cylinders across the country.
Oxygen is being transported by rail from Angul, Kalinganagar, Rourkela and Raigarh in the east to New Delhi and the capital region in the north, Railway Board chairman Suneet Sharma said.
"We have carried 150 tonnes of oxygen to Uttar Pradesh and Maharashtra until now and by tonight we will move 150 tonnes more. About Delhi, we are readying four tankers from Jindal Steel Plant in Raigarh," Mr Sharma said on Tuesday.
India's coronavirus death toll neared the bleak milestone of 200,000 after another 2,771 fatalities were reported on Tuesday.
Over the previous 24 hours, India recorded 323,144 new cases – slightly below its fifth day of global record increases that reached 352,991 on Monday.
The armed forces pledged urgent medical aid to help battle the staggering surge in infections.
Chief of Defence Staff Gen Bipin Rawat said late on Monday that oxygen would be released from armed forces reserves and retired military medical personnel would join health centres that were struggling to cope with new cases.
Meanwhile, the country's Election Commission banned all victory processions after assembly polls are held in all states, sources told PTI.
Nations including Britain, Germany, and the US pledged aid, while Indian Americans in US Congress and the technology sector joined forces to help.
The US said it would send a “strike team” of health experts and officials to India to assist. The US will also ship drugs, vaccine chemicals and other resources.
A shipment of vital medical supplies from the UK, including 100 ventilators and 95 oxygen concentrators, arrived in Delhi early on Tuesday, Reuter's partner ANI reported.
France will also send oxygen generators that can provide year-long oxygen for patients in up to 250 beds, its embassy said.
On Tuesday, France announced a "solidarity mission" for India under which it will send oxygen generation plants, ventilators and other medical supplies to support the country in its fight against the pandemic.
France's ambassador to India, Emmanuel Lenain, said the "massive solidarity mission" would be supported by French companies in India and the EU.