(AP) — As a deep freeze sets in across half the country, officials are urging people to help those most vulnerable, especially the homeless and the elderly. Forecasters are warning people to be wary of hypothermia and frostbite from the arctic blast that’s gripping a large swath from the Midwest to the Northeast.

The prolonged, dangerous cold weather has sent advocates for the homeless scrambling to get people off the streets and to bring in extra beds for them. Health officials say older people are at increased risk from such severe cold, from medication side effects to falling risks. They encouraged people to check on family members, friends and neighbors.

Animal advocates are urging people to remember their pets and not to leave them outside.