Bitterly cold temperatures are gripping New York City, bringing some of the coldest conditions residents have faced in years as officials step up efforts to keep people safe.

Warming centers have opened citywide, including about two dozen locations in the Bronx and Brooklyn. One site, Gompers High School in Mott Haven, had not received visitors as of reporting time, but school safety officials said the center is prepared to provide food and a warm, safe place for anyone seeking relief.

City officials warn that the frigid weather can cause frostbite on exposed skin in as little as 30 minutes. The city has reported at least 17 outdoor deaths so far, with more than half linked to hypothermia.

Officials are urging anyone who needs help staying warm to use the available resources. “The homeless population has increased in the past few years, and something like this is very, very important for the community,” one resident said.

City leaders are also encouraging New Yorkers to look out for one another. Anyone who sees a person experiencing homelessness and in need of shelter is urged to call 311 so agencies can help connect them with a warm space. Residents are also encouraged to direct those in need to nearby warming centers.