NEW DELHI — Mask-wearing protesters took to the streets of India’s capital Sunday as the city remained blanketed under a cloud of toxic smoke that has lingered for a week and sparked anger at the government’s slow response.

Thousands of schools have been shuttered, cricket matches canceled and residents warned to stay inside as the air pollution crisis in New Delhi and the surrounding metropolitan region – deemed an “emergency situation” by the environment minister Saturday – stretched into its seventh day.

Patients with breathing problems inundated hospitals and doctor’s clinics, and residents waited in line to buy pricey face masks, which often sold out.

“We have never seen something like this. This time things are really bad,” said P.S. Walia, 44, who was at a protest Sunday. He has shuttered his house, stopped taking morning walks and kept his two kids indoors this past week to protect them from the stinging air.

Experts said low winds, holiday fireworks residue and crop-burning in neighboring states contributed to the haze, which reduced visibility at the airport to a 17-year low last week.

Air-quality data from the U.S. Embassy’s air monitor this week averaged more than six times the level of particulate pollutant deemed acceptable by the Environmental Protection Agency.

On Sunday, Delhi’s chief minister, Arvind Kerjiwal, said the city would undertake emergency measures to address the “need of the hour,” including banning construction activity for five days, limiting diesel-generator use, water-treating dusty roads and temporarily closing a coal-fired power plant. Schools will remain shut for three days, he said.